Silver halide photographic emulsion and light-sensitive material using the same
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a silver halide photographic emulsion and a photographic light-sensitive material containing this emulsion and, more particularly, to a silver halide photographic emulsion having a low fog and a high sensitivity and a photographic light-sensitive material containing this emulsion. 
     2. Description of the Related Art 
     Silver halide photographic emulsions for use in silver halide photographic light-sensitive materials are normally subjected to chemical sensitization using various chemical substances in order to obtain, e.g., desired sensitivities and gradations. Representative methods of the chemical sensitization are sulfur sensitization, selenium sensitization, noble metal sensitization using, e.g., gold, and combinations of these sensitization methods. 
     Recently, strong demands have arisen for a high sensitivity, a good graininess, and a high sharpness of a silver halide photographic light-sensitive material, and for rapid processing obtained by increasing, e.g., the rate of development of the material, and so various improvements have been made for the above sensitization methods. 
     Among the above sensitization methods, the selenium sensitization is disclosed in, e.g., U.S. Pat. Nos. 1,574,944, 1,602,592, 1,623,499, 3,297,446, 3,297,447, 3,320,069, 3,408,196, 3,408,197, 3,442,653, 3,420,670 and 3,591,385, French Patents 2,093,038 and 2,093,209, JP-B-52-34491 (&#34;JP-B&#34; means Published Examined Japanese Patent Application), JP-B-52-34492, JP-B-53-295, JP-B-57-22090, JP-A-59-180536 (&#34;JP-A&#34; means Published Unexamined Japanese Patent Application), JP-A-59-185330, JP-A-59-181337, JP-A-59-187338, JP-A-59-192241, JP-A-60-150046, JP-A-60-151637, JP-A-61-246738, JP-A-3-111838, JP-A-3-148648, British Patents 255,846 and 861,984, and H. E. Spencer et al., &#34;Journal of Photographic Science,&#34; vol. 31, pages 158 to 169 (1983). 
     On the other hand, it is considered preferable in terms of uniformity of chemical sensitization and development properties that silver iodide (iodide ion) contents of individual silver halide grains be uniform in order to obtain a high sensitivity. 
     JP-A-2-68538 (Japanese Patent Application No. 63-220187) discloses a technique of eliminating a nonuniform halide distribution both inside each grain and between individual grains by using a halogen ion slow releasing agent or fine silver halide grains as a halogen ion supply source in place of a conventionally used aqueous halogen salt solution during formation of silver halide grains. 
     The above patent application, however, does not report that formation of silver halide grains performed while rapidly producing iodide ions is important in the manufacture of an emulsion with a high sensitivity and a low fog. 
     Generally, the selenium sensitization has a larger sensitizing effect than that obtained by the sulfur sensitization commonly performed in this field of art but often tends to increase fog and to readily cause soft tone. Although many of the above known patents are for improving these drawbacks, they can provide only unsatisfactory results so far. Therefore, a strong demand has arisen for particularly a radical improvement for suppressing generation of fog. 
     In addition, a significant increase in sensitivity can be obtained by especially when the sulfur sensitization or the selenium sensitization is combined with the gold sensitization, but also the fog increases at the same time. The increase in fog in gold-selenium sensitization is larger than that in gold-sulfur sensitization. So development of a technique capable of suppressing generation of fog has been strongly desired. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a silver halide photographic emulsion having an appropriate gradation, a low fog, and a high sensitivity, and a light-sensitive material using the same. 
     The above object of the present invention is achieved by a silver halide photographic emulsion comprising silver halide grains which are formed while iodide ions are rapidly being generated to form a silver iodide-containing region in the silver halide grains, and which are chemically sensitized with selenium sensitizers. 
     The present invention makes it possible to sufficiently take advantage of the sensitizing effects of the selenium sensitization, that are difficult to utilize by conventional techniques. 
     In one embodiment, the iodide ions are generated from an iodide ion-releasing agent placed in a reactor vessel, 50 to 100% of which agent complete release of iodide ions within 180 consecutive seconds in the reaction vessel. 
     Usually, the iodide ions are rapidly generated from an iodide ion-releasing agent by a reaction with an iodide ion release-controlling agent. The iodide-forming reaction can be expressed as a second-order reaction essentially proportional to a concentration of an iodide ion-releasing agent and a concentration of an iodide ion release-controlling agent, and a rate constant of the second-order reaction is 1,000 to 5×10 -3  M -1  ·sec -1 . 
     Preferably, the iodide ion-releasing agent is represented by Formula (I) below: 
     
         R--I                                                       Formula (I) 
    
     where R represents a monovalent organic residue which releases the iodine atom, I, in the form of iodide ions upon reacting with a base and/or a nucleophilic reagent. 
     A photographic light-sensitive material containing a silver halide photographic emulsion of the invention is also within the scope of the present invention. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in more detail below. 
     An iodide ion-releasing agent represented by Formula (I) of the present invention overlaps in part with compounds used to obtain a uniform halogen composition in each silver halide grain and between individual grains in JP-A-2-68538 described above. 
     It is, however, totally unexpected for the present inventors to find that a silver halide emulsion having a low fog, and a high sensitivity can be obtained by performing formation of silver halide grains while iodide ions are rapidly being generated from of an iodide ion-releasing agent represented by Formula (I). 
     An iodide ion-releasing agent represented by Formula (I) below of the present invention will be described in detail. 
     
         R--I                                                       Formula (I) 
    
     where R represents a monovalent organic residue which releases the iodine atom, I, in the form of iodide ions upon reacting with a base and/or a nucleophilic reagent. 
     The details of a compound represented by Formula (I) will be described. Preferable examples of R are an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 or 3 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, an acyl group having 1 to 30 carbon atoms, a carbamoyl group, an alkyl or aryloxycarbonyl group having 2 to 30 carbon atoms, an alkyl or arylsulfonyl group having 1 to 30 carbon atoms, and a sulfamoyl group. 
     R is preferably one of the above groups having 20 or less carbon atoms, and most preferably one of the above groups having 12 or less carbon atoms. 
     Groups each having the number of carbon atoms, which falls within this range, are preferable in view of their solubility and the amount in which they are used. 
     It is also preferable that R be substituted, and examples of preferable substituents are as follows. These substituents may be further substituted by other substituents. 
     Examples are a halogen atom (e.g., fluorine, chlorine, bromine, and iodine), an alkyl group (e.g., methyl, ethyl, n-propyl, isopropyl, t-butyl, n-octyl, cyclopentyl, and cyclohexyl), an alkenyl group (e.g., allyl, 2-butenyl, and 3-pentenyl), an alkynyl group (e.g., propargyl and 3-pentynyl), an aralkyl group (e.g., benzyl and phenethyl), an aryl group (e.g., phenyl, naphthyl, and 4-methylphenyl), a heterocyclic group (e.g., pyridyl, furyl, imidazolyl, piperidyl, and morpholyl), an alkoxy group (e.g., methoxy, ethoxy, and butoxy), an aryloxy group (e.g., phenoxy and naphthoxy), an amino group (e.g., unsubstituted amino, dimethylamino, ethylamino, and anilino), an acylamino group (e.g., acetylamino and benzoylamino), a ureido group (e.g., unsubstituted ureido, N-methylureido, and N-phenylureido), a urethane group (e.g., methoxycarbonylamino and phenoxycarbonylamino), a sulfonylamino group (e.g., methylsulfonylamino and phenylsulfonylamino), a sulfamoylamino group (e.g., sulfamoyl, N-methylsulfamoyl, and N-phenylsulfamoyl), a carbamoyl group (e.g., carbamoyl, diethylcarbamoyl, and phenylcarbamoyl), a sulfonyl group (e.g., methylsulfonyl and benzenesulfonyl), a sulfinyl group (e.g., methylsulfinyl and phenylsulfinyl), an alkyloxycarbonyl group (e.g., methoxycarbonyl and ethoxycarbonyl), an aryloxycarbonyl group (e.g., phenoxycarbonyl), an acyl group (e.g., acetyl, benzoyl, formyl, and pivaloyl), an acyloxy group (e.g., acetoxy and benzoyloxy), an amido-phosphoryl group (e.g., N,N-diethylamido-phosphoryl), an alkylthio group (e.g., methylthio and ethylthio), an arylthio group (e.g., a phenylthio group), a cyano group, a sulfo group, a carboxyl group, a hydroxy group, a phosphono group, and a nitro group. 
     More preferable substituents for R are a halogen atom, an alkyl group, an aryl group, a 5- or 6-membered heterocyclic group containing at least one O, N, or S, an alkoxy group, an aryloxy group, an acylamino group, a sulfamoyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, an aryloxycarbonyl group, an acyl group, a sulfo group, a carboxyl group, a hydroxy group, and a nitro group. 
     Most preferable substituents for R are a hydroxy group, a carbamoyl group, a lower alkylsulfonyl group, and a sulfo group (including its salt), when substituted on an alkylene group, and a sulfo group (including its salt), when substituted on a phenylene group. 
     A compound represented by Formula (I) of the present invention is preferably a compound represented by Formula (II) or (III) below. 
     A compound represented by Formula (II) of the present invention will be described below. ##STR1## 
     In Formula (II), R 21  represents an electron-withdrawing group, and R 22  represents a hydrogen atom or a substitutable group. 
     n 2  represents an integer from 1 to 6. n 2  is preferably an integer from 1 to 3, and most preferably 1 or 2. 
     The electron-withdrawing group represented by R 21  is preferably an organic group having a Hammett σ p , σ m , or σ I  value larger than 0. 
     The Hammett σ p  or σ m  value is described in &#34;Structural Activity Correlation of Chemicals&#34; (Nanko Do), page 96 (1979), and the Hammett σ I  value is described in the same literature, page 105. So the values can be selected on the basis of these tables. 
     Preferable examples of R 21  are a halogen atom (e.g., fluorine, chlorine, and bromine), a trichloromethyl group, a cyano group, a formyl group, a carboxylic acid group, a sulfonic acid group, a carbamoyl group (e.g., unsubstituted carbamoyl and diethylcarbamoyl), an acyl group (e.g., acetyl and benzoyl), an oxycarbonyl group (e.g., methoxycarbonyl and ethoxycarbonyl), a sulfonyl group (e.g., methanesulfonyl and benzenesulfonyl), a sulfonyloxy group (e.g., methanesulfonyloxy), a carbonyloxy group (e.g., acetoxy), a sulfamoyl group (e.g., unsubstituted sulfamoyl and dimethylsulfamoyl), and a heterocyclic group (e.g., 2-thienyl, 2-benzoxazolyl, 2-benzothiazolyl, 1-methyl-2-benzimidazolyl, 1-tetrazolyl, and 2-quinolyl). Carbon-containing groups of R 21  preferably contain 1 to 20 carbon atoms. 
     Examples of the substitutable group represented by R 22  are those enumerated above as the substituents for R. A plurality of R 22  &#39;s present in a molecule may be the same or different. 
     It is preferable that one-half or more of a plurality of R 22  &#39;s contained in a compound represented by Formula (II) be hydrogen atoms. 
     R 21  and R 22  may be further substituted. Preferable examples of the substituents are those enumerated above as the substituents for R. 
     Also, R 21  and R 22  or two or more R 22  &#39;s may combine together to form a 3- to 6-membered ring. 
     A compound represented by Formula (III) of the present invention will be described below. 
     Formula (III) ##STR2## 
     In Formula (III), R 31  represents an R 33  O-group, an R 33  S-group, an (R 33 ) 2  N-group, an (R 33 ) 2  P-group, or phenyl, wherein R 33  represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 or 3 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 4 to 30 carbon atoms. 
     Groups each having the number of carbon atoms, which falls within this range, are preferable in view of their solubility and the amount in which they are used. 
     If R 31  represents the (R 33 )2N-group or the (R 33 ) 2  P-group, two R 33  groups may be the same or different. 
     R 32  and n 3  have the same meanings as R 22  and n2 in Formula (II), and a plurality of R 32  &#39;s may be the same or different. 
     Examples of the substitutable group represented by R 32  are those enumerated above as the substituents for R. 
     n 3  is most preferably 1, 2, 4, or 5. 
     R 31  and R 32  may be further substituted. Preferable examples of the substituents are those enumerated above as the substituents for R. 
     Also, R 31  and R 32 , or two or more R 32  &#39;s may bond together to form a ring. 
     Practical examples of compounds represented by Formulas (I), (II), and (III) of the present invention will be described below, but the present invention is not limited to these examples. ##STR3## 
     The iodide ion-releasing agent of the present invention can be synthesized in accordance with the following synthesizing methods: 
     J. Am. Chem. Soc., 76, 3227-8 (1954), J. Org. Chem., 16, 798 (1951), Chem. Ber., 97, 390 (1964), Org. Synth., V, 478 (1973), J. Chem. Soc., 1951, 1851, J. Org. Chem., 19, 1571 (1954), J. Chem. Soc., 1952, 142, J. Chem. Soc., 1955, 1383, Angew, Chem., Int. Ed., 11, 229 (1972), Chem Commu., 1971, 1112. 
     The iodide ion-releasing agent of the present invention releases iodide ion upon reacting with an iodide ion release-controlling agent (a base and/or a nucleophilic reagent). Preferable examples of the nucleophilic reagent for this purpose are chemical species listed below: 
     Hydroxide ion, sulfite ion, hydroxylamine, thiosulfate ion, metabisulfite ion, hydroxamic acids, oximes, dihydroxybenzenes, mercaptanes, sulfinate, carboxylate, ammonia, amines, alcohols, ureas, thioureas, phenols, hydrazines, hydrazides, semicarbazides, phosphines, and sulfides. 
     In the present invention, the rate and timing at which iodide ions are released can be controlled by controlling the concentration of a base or a nucleophilic reagent, the addition method, or the temperature of a reaction solution. A preferable example of the base is alkali hydroxide. 
     The range of concentration of the iodide ion-releasing agent and the iodide ion release-controlling agent for use in the rapid production of iodide ions is preferably 1×10 -7  to 20M, more preferably 1×10 -5  to 10M, further preferably 1×10 -4  to 5M, and most preferably 1×10 -3  to 2M. 
     If the concentration exceeds 20M, the total amount of the iodide ion-releasing agent and the iodide ion release-controlling agent, both having a great molecular weight, will be excessive for the volume of the grain formation vessel used. On the other hand, if the concentration is less than 1×10 -7  M, the rate of reaction of releasing iodide ions will be too low, making it difficult to produce iodide ions rapidly. 
     The range of temperature is preferably 30° to 80° C., more preferably 35° to 75° C., and most preferably 35° to 60° C. 
     Generally, the rate of reaction of releasing iodide ions is too high at high temperatures over 80° C., and is too low at low temperatures below 30° C. The temperature range within which to use the iodide ion-releasing agent is therefore limited. 
     In the present invention, changes in pH of the solution can be used if the base is used in releasing iodide ions. 
     In this case, the range of pH for controlling the rate and timing at which iodide ions are released is preferably 2 to 12, more preferably 3 to 11, and particularly preferably 5 to 10. The pH is most preferably 7.5 to 10.0 after the control. Hydroxide ion determined by the ion product of water serves as a control agent even under a neutral condition of pH 7. 
     It is also possible to use the nucleophilic reagent and the base together. Here again, the rate and timing at which iodide ion is released may be controlled by controlling the pH within the above range. 
     The range of amount of iodide ions released from the iodide ion-releasing agent is preferably 0.1 to 20 mole %, more preferably 0.3 to 15 mole %, and most preferably 1 to 10 mole % with respect to the total amount of the silver halides. 
     The iodide ions can be released in any amount ranging from 0.1 to 20 mole % that is suitable for the purpose the ions are used. If the amount exceeds 20 mole %, however, the development speed will decrease in most cases. 
     When iodine atoms are to be released in the form of iodide ions from the iodide ion-releasing agent, iodine atoms may be either released completely or partially left undecomposed. 
     The rate at which iodide ions are released from the iodide ion-releasing agent will be described below by way of practical examples. 
     In the present invention, it is preferable to form a silver halide phase containing silver iodide on the edges of a tabular grain while iodide ions are rapidly being generated during the process of introducing dislocation lines into the tabular grain, in order to introduce dislocation lines at a high density. 
     If the supply rate of iodide ions is too low, i.e., if the time required to form a silver halide phase containing silver iodide is too long, the silver halide phase containing silver iodide dissolves again during the formation, and the dislocation density decreases. 
     On the other hand, supplying iodide ions slowly is preferable in performing grain formation such that no nonuniformity is produced in a distribution of dislocations between individual grains. 
     It is therefore important that iodide ions be rapidly generated without causing any locality (nonuniform distribution). 
     When an iodide ion-releasing agent or an iodide ion release-controlling agent to be used together therewith is added through an inlet to a reaction solution placed in a grain formation vessel, a locality with a high concentration of added agent may be formed near the inlet. Thus, correspondingly, a locality of generated iodide ions is produced, since an iodide ion release reaction proceeds very quickly. 
     The rate at which iodide ions released are deposited on a host grain is very high, and grain growth occurs in a region near the addition inlet where the locality of the iodide ions is large. The result is grain growth nonuniform between individual grains. 
     Therefore, the iodide ion-releasing rate must be selected so as not to cause locality of iodide ions. 
     In conventional methods (e.g., a method of adding an aqueous potassium iodide solution), iodide ions are added in a free state even when an aqueous potassium iodide solution is diluted before the addition. This limits the reduction in locality of iodide ions. 
     That is, it is difficult for the conventional methods to perform grain formation without causing nonuniformity between grains. 
     The present invention, however, which can control the iodide ion-releasing rate, makes it possible to reduce the locality of iodide ions compared to the conventional methods. 
     In the example described above, dislocation lines can be introduced at a high density and uniformly between individual grains compared to the conventional methods by the use of the present invention capable of performing grain formation while producing iodide ions rapidly without causing any locality. 
     In the present invention, the iodide ion-releasing rate can be determined by controlling the temperature and the concentrations of the iodide ion-releasing agent and the iodide ion release-controlling agent and therefore can be selected in accordance with the intended use. 
     In the present invention, a preferable iodide ion-releasing rate is the one at which 50 to 100% of the total weight of the iodide ion-releasing agent present in a reaction solution in a grain formation vessel complete release of iodide ion within 180 consecutive seconds, more preferably within 120 consecutive seconds, and most preferably within 60 consecutive seconds. 
     Preferably, the iodide ions should be released over at least 1 second. 
     The words &#34;180 consecutive seconds&#34; means a period for which the reaction of releasing iodide ions continues. The iodide ion-releasing period may be measured, starting at any time during the continuous reaction. If the iodide ions are released during two or more periods, set part from one another, the iodide ion releasing period may be measured, starting at any time during the first period or any other period. The ion releasing rate may be determined at said time during the first period or any other period. 
     A releasing rate at which the time exceeds 180 seconds is generally low, and a releasing rate at which the time exceeds less than 1 second is generally low. The releasing rate is limited. This similarly applied to a releasing rate at which the amount of the iodide ion-releasing agent is less than 50%. 
     &#34;Completion of release of iodide ions&#34; means that all the iodine contained in a particular iodide ion-releasing agent is released from the releasing agent in the form of ions. For example, in the case of an iodide ion-releasing agent having one iodine in the molecule, the release of iodide ions is completed when the one iodine is released from the releasing agent. In the case of an iodine ion-releasing agent having two or more iodines in the molecule, the release of iodide ions is completed when all of the two or more iodines are released therefrom. 
     A releasing rate at which the time exceeds 180 seconds is generally low, and so its use conditions are limited. This similarly applies to a releasing rate at which the amount of the iodide ion-releasing agent is less than 50%. 
     A more preferable rate is the one at which 100 to 70% of the iodide ion-releasing agent present in a reaction solution in a grain formation vessel complete release of iodide ion within 180 consecutive seconds. The rate is further preferably the one at which 100 to 80%, and most preferably 100 to 90% complete release of iodide ion within 180 consecutive seconds. 
     When the reaction of rapidly producing iodide ions is represented by a second-order reaction essentially proportional to the concentration of the iodide ion-releasing agent and that of the iodide ion release-controlling agent (under water, 40° C.), the rate constant of the second-order reaction in the present invention is preferably 1,000 to 5×10 -3  (M -1  ·sec -1 ), more preferably 100 to 5×10 -2  (M -1  ·sec -1 ), and most preferably 10 to 0.1 (M -1  ·sec -1 ). 
     The &#34;essentially second-order reaction&#34; means that the coefficient of correlation is 1.0 to 0.8. The following is representative examples of a second-order reaction rate constant k (M -1  ·sec -1 ) measured under the conditions considered to be a pseudo first-order reaction: the concentration of the iodide ion-releasing agent ranging from 10 -4  to 10 -5  M, the concentration of the iodide ion release control agent ranging from 10 -1  to 10 -4  M, under water, and 40° C. 
     
         ______________________________________                                    
Compound No.                                                              
          Iodide ion release-controlling agent                            
                                k                                         
______________________________________                                    
11        Hydroxide ion         1.3                                       
1         Sulfite ion           1 × 10.sup.-3                       
                                or less                                   
2         &#34;                     0.29                                      
58        &#34;                     0.49                                      
63        &#34;                     1.5                                       
22        Hydroxide ion         720                                       
______________________________________                                    
 
    
     If k exceeds 1,000, the release is too fast to control; if it is less than 5×10 -3 , the release is too slow to obtain the effect of the present invention. 
     The following method is favorable to control the release of iodide ions in the present invention. 
     That is, this method allows the iodide ion-releasing agent, added to a reaction solution in a grain formation vessel and already distributed uniformly, to release iodide ions uniformly throughout the reaction solution by changing the pH, the concentration of a nucleophilic substance, or the temperature, normally by changing from a low pH to a high pH. 
     It is preferable that alkali for increasing the pH during release of iodide ions and the nucleophilic substance be added in a condition in which the iodide ion-releasing agent is distributed uniformly throughout the reaction solution. 
     More specifically, in the present invention, iodide ions, which are to react with silver ions, are rapidly generated in a reaction system in order to form silver halide grains containing silver iodide (e.g., silver iodide, silver bromoiodide, silver bromochloroiodide, or silver chloroiodide). In most cases, the iodide ion-releasing agent of this invention is added, if necessary along with another halogen ion source (e.g., KBr), to the reaction system which uses, as a reaction medium, an aqueous gelatin solution containing silver ions due to addition of, for example, silver nitrate, or containing silver halide grains (e.g., silver bromoiodide grains), and the iodide ion-releasing agent is distributed uniformly in the reaction system by a known method (such as stirring). At this stage the reaction system has a low pH value and is weakly acidic, and the iodide ion-releasing agent does not release iodide ions rapidly. 
     An alkali (e.g., sodium hydroxide or sodium sulfite) is then added, as an iodide ion release-controlling agent, to the reaction system, thereby increasing the pH of the system to the alkaline side (preferably, to 7.5 to 10). As a result, iodide ions are rapidly released from the iodide ion-releasing agent. The iodide ions react with the silver ions or undergo halogen conversion with the silver halide grains, thus forming a silver iodide-containing region. 
     As has been indicated, the reaction temperature usually ranges from 30° to 80° C., more preferably 35° to 75° C., and most preferably 35° to 60° C. The iodide ion-releasing agent releases iodide ions usually at such a rate that 50 to 100% of the agent completes release of iodide ions within a consecutive period of 1 second to 180 seconds, starting at the time of adding the alkali. To make the iodide ion-releasing agent to release iodide ions at such a rate, which iodide ion-releasing agent and which iodide ion release control agent should be used in combination in which amounts they should be used are determined in accordance with the second-order reaction rate constant described above. 
     In order to distribute the alkali uniformly in the reaction system (that is, to produce silver iodide uniformly), it is desirable that the alkali be added while the reaction system is being vigorously stirred by means of, for example, controlled double jet method. 
     The emulsion grain of the present invention will be described below. 
     The emulsion grain of the present invention is a silver halide containing silver iodide. 
     The emulsion grain of the present invention contains at least one of a silver iodide phase, a silver bromoiodide phase, a silver bromochloroiodide phase, and a silver iodochloride phase. 
     The emulsion grain may also contain another silver salt, e.g., silver rhodanate, silver sulfide, silver selenide, silver carbonate, silver phosphate, and an organic acid silver salt, as another grain or as a portion of the silver halide grain. 
     The range of silver iodide content of the emulsion grain of the present invention is preferably 0.1 to 20 mole %, more preferably 0.3 to 15 mole %, and most preferably 1 to 10 mole %. 
     The silver iodide content can be released in any amount ranging from 0.1 to 20 mole % that is suitable for the purpose the ions are used. If the amount exceeds 20 mole %, however, the development speed will decrease in most cases. 
     The emulsion grain of the present invention preferably has one of the following structures based on a halogen composition. 
     (1) A grain having one or more covering shells on a substrate grain 
     It is preferable to form the inner shell or the outermost shell of a double structure, a triple structure, a fourfold structure, a fivefold structure, . . . , or a multiple structure by using the iodide ion-releasing method of the present invention. 
     (2) A grain in which one or more layers not completely covering a substrate grain are deposited on the substrate grain 
     It is preferable to form the inner layer or the outermost layer of a two-layered structure, a three-layered structure, a four-layered structure, a five-layered structure, . . . , or a multi-layered structure by using the iodide ion-releasing method of the present invention. 
     (3) A grain in which epitaxial growth is performed at selected portions of a substrate grain 
     It is preferable to form the epitaxial portions on the corners, the edges, and the major faces of a grain by using the iodide ion-releasing method of the present invention. 
     It is preferable that the compositions of the covering shells, the deposited layers, and the epitaxial portions of a silver halide containing silver iodide formed by the use of the iodide ion-releasing method of the present invention have high silver iodide contents. 
     Although these silver halide phases may be any of silver iodide, silver bromoiodide, silver bromochloroiodide, and silver iodochloride, they are preferably silver iodide or silver bromoiodide, and more preferably silver iodide. 
     When the silver halide phase is silver bromoiodide, a silver iodide (iodide ion) content is preferably 1 to 45 mole %, more preferably 5 to 45 mole %, and most preferably 10 to 45 mole %. 
     If the silver iodide content is less than 1 mole %, the dye adsorption will not be increased sufficiently, the intrinsic sensitivity will not be improved sufficiently, and misfit required for introducing dislocations will not be formed. If the content exceeds 45 mole %, silver iodide can no longer be a solid solubility limit. 
     It is preferable to prepare silver halide grains containing dislocations by the use of the iodide ion releasing method of the present invention. 
     A dislocation is a linear lattice defect at the boundary between a region already slipped and a region not slipped yet on a slip plane of crystal. 
     Dislocation lines in silver halide crystal are described in, e.g., 1) C. R. Berry. J. Appl. Phys., 27, 636 (1956), 2) C. R. Berry, D. C. Skilman, J. Appl. Phys., 35, 2165 (1964), 3) J. F. Hamilton, Photo Sci. Eng., 11, 57 (1967), 4) T. Shiozawa, J. Soc. Sci. Jap., 34, 16 (1971), and 5) T. Shiozawa, J. Soc. Phot. Sci. Jap., 35, 213 (1972). Dislocation lines can be analyzed by an X-ray diffraction method or a direct observation method using a low-temperature transmission electron microscope. 
     In direct observation of dislocation lines using a transmission electron microscope, silver halide grains, carefully taken out from an emulsion so as not to apply a pressure at which dislocation lines are produced in the grains, are placed on a mesh for electron microscopic observation. While the sample is cooled in order to prevent damages (e.g., print out) due to electron rays, the observation is performed by a transmission method. 
     In this case, as the thickness of a grain is increased, it becomes more difficult to transmit electron rays through it. Therefore, grains can be observed more clearly by using an electron microscope of a high voltage type (200 kV or more for a thickness of 0.25 μm). 
     Effects that dislocation lines have on photographic performance are described in G. C. Farnell, R. B. Flint, J. B. Chanter, J. Phot. Sci., 13, 25 (1965). This literature demonstrates that in a large tabular silver halide grain with a high aspect ratio, a location at which a latent image speck is formed has a close relationship to a defect in the grain. 
     JP-A-63-220238 and JP-A-1-201649 disclose tabular silver halide grains to which dislocation lines are introduced intentionally. 
     These patent applications indicate that tabular grains to which dislocation lines are introduced are superior to those having no dislocation lines in photographic characteristics, such as sensitivity and reciprocity. 
     A method of introducing dislocation lines into a silver halide grain will be described below. 
     In the present invention, it is preferable to introduce dislocation lines into a silver halide grain as follows. 
     That is, after silver halide grains serving as substrate grains are prepared, silver halide phases (silver halide covering shells, deposited layers, and epitaxial growth described above) containing silver iodide are formed on these substrate grains. 
     As mentioned earlier, it is preferable that the silver iodide contents of these silver halide phases be as high as possible. 
     The silver iodide content of the substrate grain is preferably 0 to 15 mole %, more preferably 0 to 12 mole %, and most preferably 0 to 10 mole %. 
     A halogen amount to be added to form this high silver iodide content phase on the substrate grain is preferably 2 to 15 mole %, more preferably 2 to 10 mole %, and most preferably 2 to 5 mole % with respect to a silver amount of the substrate grain. 
     If the halogen content is less than 2 mole %, dislocation lines cannot be easily introduced into the grains. If the halogen content exceeds 15 mole %, the development rate will decrease. The halogen content is selected in accordance with the purpose for which the emulsion will be used. 
     The high silver iodide content phase falls within a range of preferably 5 to 80 mole %, more preferably 10 to 70 mole %, and most preferably 20 to 60 mole % with respect to a silver amount of an overall grain. 
     If the high silver iodide content phase is less than 5 mole % or exceeds 80 mole %, dislocation lines cannot easily be introduced into the grains to increase the sensitivity of the emulsion. 
     A location on the substrate grain where the high silver iodide content phase is to be formed can be selected as desired. Although the high silver iodide content phase can be formed to cover the substrate grain or in a particular portion, it is preferable to control the positions of dislocation lines inside a grain by epitaxially growing the phase at a specific portion selected. 
     In this case, it is possible to freely select the composition of a halogen to be added, the addition method, the temperature of a reaction solution, the pAg, the solvent concentration, the gelatin concentration, and the ion intensity. 
     Thereafter, dislocation lines can be introduced by forming a silver halide shell outside the phases. 
     The composition of this silver halide shell may be any of silver bromide, a silver bromoiodide, and silver bromochloroiodide, but it is preferably silver bromide or silver bromoiodide. 
     When the silver halide shell consists of silver bromoiodide, the silver iodide content is preferably 0.1 to 12 mole %, more preferably 0.1 to 10 mole %, and most preferably 0.1 to 3 mole %. 
     If the silver iodide content is less than 0.1 mole %, the dye adsorption will not be increased sufficiently and the development will not be promoted sufficiently. If the content exceeds 12 mole %, the development rate will decrease. 
     In the above process of introducing dislocations, the temperature is preferably 30° to 80° C., more preferably 35° to 75° C., and most preferably 35° to 60° C. 
     If the temperature is lower than 30° C. or higher than 80° C., it can hardly be controlled in the apparatus employed in most cases. To control the temperature outside the range of 30° to 80° C., it would be necessary to use an apparatus having greater ability, which is undesirable in view of manufacturing cost. 
     A preferable pAg is 6.4 to 10.5. 
     In the case of tabular grains, the positions and the numbers of dislocation lines of individual grains viewed in a direction perpendicular to their major faces can be obtained from a photograph of the grains taken by using an electron microscope. 
     Note that dislocation lines can or cannot be seen depending on the angle of inclination of a sample with respect to electron rays. Therefore, in order to obverse dislocation lines without omission, it is necessary to obtain the positions of dislocation lines by observing photographs of the same grain taken at as many sample inclination angles as possible. 
     In the present invention, it is preferable to take five photographs of the same grain at inclination angles different by a 5° step by using a high-voltage electron microscope, thereby obtaining the positions and the number of dislocation lines. 
     In the present invention, when dislocation lines are to be introduced inside a tabular grain, the positions of the dislocation lines may be limited to the corners or the fringe portion of the grain, or the dislocation lines may be introduced throughout the entire major faces. It is, however, preferable to limit the positions of the dislocations to the fringe portion. 
     In the present invention, the &#34;fringe portion&#34;  means the peripheral region of a tabular grain. More specifically, the fringe portion is a region outside a certain position where, in a distribution of silver iodide from the edge to the center of a tabular grain, a silver iodide content from the edge side exceeds or becomes lower than the average silver iodide content of the overall grain for the first time. 
     In the present invention, it is preferable to introduce dislocation lines at a high density inside a silver halide grain. 
     When dislocation lines are to be introduced inside tabular grains, each grain has preferably 10 or more, more preferably 30 or more, and most preferably 50 or more dislocation lines in its fringe portion when the dislocation lines are counted by the method using an electron microscope described above. 
     If dislocation lines are densely present or cross each other, it is sometimes impossible to accurately count the dislocation lines per grain. 
     Even in these situations, however, dislocation lines can be roughly counted to such an extent as in units of 10 lines. 
     It is desirable that the distribution of dislocation lines between individual silver halide grains be uniform. 
     In the present invention, when dislocation lines are to be introduced into tabular grains, tabular grains each having 10 or more dislocation lines in its fringe portion preferably occupy 100 to 50% (number), more preferably 100 to 70%, and most preferably 100 to 90% of all grains. 
     If such tabular grains occupy less than 50% of all grains, the grains will fail to have desired uniformity. 
     In the present invention, in order to obtain the ratio of grains containing dislocation lines and the number of dislocation lines, it is preferable to directly observe dislocation lines for at least 100 grains, more preferably 200 grains or more, and most preferably 300 grains or more. 
     The tabular grain of the present invention is a silver halide grain having two parallel major faces opposing each other. 
     The tabular grain of the present invention has one twin plane or two or more parallel twin planes. 
     The twin plane is a (111) plane on both sides of which ions at all lattice points have a mirror image relationship to each other. 
     When this tabular grain is viewed from the above, the grain looks like a triangle, a hexagon, or a rounded triangle or hexagon, and have parallel outer surfaces. 
     The equivalent-circle diameter of the tabular grain of the present invention is preferably 0.3 to 10 μm, more preferably 0.4 to 5 μm, and most preferably 0.5 to 4 μm. 
     If the tabular grain has an equivalent-circle diameter of less than 0.3 μm, the advantages inherent in tabular grains cannot be utilized fully. If the tabular grain has an equivalent-circle diameter of greater than 10 μm, the emulsion will have but an insufficient resistance to pressure. 
     The thickness of the tabular grain of the present invention is preferably 0.05 to 1.0 μm, more preferably 0.08 to 0.5 μm, and most preferably 0.08 to 0.3 μm. 
     If the thickness is less than 0.05 μm, the pressure resistance of the emulsion will decrease. If the thickness exceeds 1.0 μm, the advantages inherent in tabular grains cannot be utilized fully. 
     The aspect ratio of the tabular grain of the present invention is preferably 2 to 30, and more preferably 3 to 25, and most preferably 50 to 20. 
     If the aspect ratio is less than 2, the advantages inherent in tabular grains cannot be utilized fully. If the aspect ratio exceeds 30, the pressure resistance of the emulsion will decrease. 
     The aspect ratio is a value obtained by dividing the equivalent-circle diameter of the projected area of a silver halide grain by the thickness of that grain. 
     The aspect ratio can be measured by, e.g., a replica method in which the equivalent-circle diameter of the projected area and the thickness of each grain are obtained from transmission electron micrographs. 
     In this method, the thickness is calculated from the length of the shadow of a replica. 
     In the present invention, hexagonal tabular grains, in which the ratio of a side having the maximum length to a side having the minimum length is 2 or 1, occupy preferably 100 to 50%, more preferably 100 to 70%, and most preferably 100 to 90% of the total projected area of all grains contained in an emulsion. 
     If such tabular grains occupy less than 50% of all grains, the uniformity among the grains will be degraded. 
     The emulsion of the present invention is preferably monodisperse. 
     In the present invention, a variation coefficient of a grain size distribution of all silver halide grains is preferably 20% to 3%, more preferably 15% to 3%, and most preferably 10% to 3%. 
     If the variation coefficient exceeds 20%, the uniformity among the gains will be degraded. 
     The variation coefficient of a grain size distribution is a value obtained by dividing a standard deviation of a grain size distribution of grains by an average grain size of those grains. 
     It is also preferable to form the outermost shell near the surface of a silver halide grain uniformly in each grain and between individual grains by using the iodide ion-releasing method of the present invention. 
     Forming a silver halide phase containing silver iodide near the surface of a grain is important in enhancing a dye adsorbing force and controlling a developing rate. 
     In the present invention, the &#34;grain surface&#34; means a region at a depth of about 50 Å from the surface of a grain. 
     The halogen composition in such a region can be measured by a surface analysis method, such as XPS (X-ray photoelectron spectroscopy) or ISS (ion scattering spectroscopy). 
     In the present invention, the silver iodide content of a silver halide phase formed on the surface of an emulsion grain measured by these surface analysis methods is preferably 0.1 to 15 mole %, more preferably 0.3 to 12 mole %, particularly preferably 1 to 10 mole %, and most preferably 3 to 8 mole %. 
     If the silver iodide content is less than 0.1 mole %, the dye adsorption will not be increased sufficiently and the development will not be promoted sufficiently. If the content exceeds 15 mole %, the development rate will decrease. 
     In the present invention, halogen compositions of emulsion grains are preferably uniform between the grains. 
     In the emulsion of the present invention, the variation coefficient of the distribution of silver iodide contents of individual grains is preferably 20% to 3%, more preferably 15% to 3%, and most preferably 10% to 3%. 
     If the variation coefficient of the silver iodide content distribution exceeds 20%, the uniformity among the grains will be degraded. 
     The silver iodide contents of individual emulsion grains can be measured by analyzing the composition of each grain by using an X-ray microanalyzer. 
     The variation coefficient of a silver iodide content distribution is a value obtained by dividing a variation (standard deviation) of silver iodide contents of individual grains by an average silver iodide content. 
     Selenium compounds disclosed in conventionally known patents can be used as a selenium sensitizer for use in the present invention. Normally, a labile selenium compound and/or a non-labile selenium compound is used by adding it to an emulsion and stirring the emulsion at high temperatures, preferably 40° C. or more for a predetermined time period. Preferable examples of the labile selenium compound are described in JP-B-44-15748, JP-B-43-13489, JP-A-4-25832, and JP-A-4-109240. Practical examples of the labile selenium sensitizer are isoselenocyanates (e.g., aliphatic isoselenocyanates such as allylisoselenocyanate), selenoureas, selenoketones, selenoamides, selenocarboxylic acids (e.g., 2-selenopropionic acid and 2-selenobutyric acid), selenoesters, diacylselenides (e.g., bis(3-chloro-2,6-dimethoxybenzoyl)selenide), selenophosphates, phosphineselenides, and colloidal metal selenium. 
     Although preferable examples of the labile selenium compound are described above, the present invention is not limited to these examples. It is generally agreed by those skilled in the art that the structure of a labile selenium compound used as a sensitizer for a photographic emulsion is not so important as long as selenium is labile, and that the organic part of a molecule of the selenium sensitizer has no important role except the role of carrying selenium and keeping it in a labile state in an emulsion. In the present invention, therefore, labile selenium compounds in this extensive concept are advantageously used. 
     Examples of the non-labile selenium compound used in the present invention are those described in JP-B-46-4553, JP-B-52-34492, and JP-B-52-34491. Specific examples of the non-labile selenium compound are selenious acid, potassium selenocyanide, selenazoles, quaternary salts of selenazoles, diarylselenide, diaryldiselenide, dialkylselenide, dialkyldiselenide, 2-selenazolidinedione, 2-selenoxazolidinethione, and derivatives of these compounds. 
     Among these selenium compounds, those preferably used in the present invention are compounds represented by Formulas (IV) and (V) below. 
     Formula (IV) ##STR4## wherein Z 1  and Z 2  may be the same or different and each represents an alkyl group (e.g., methyl, ethyl, t-butyl, adamantyl, and t-octyl), an alkenyl group (e.g., vinyl and propenyl), an aralkyl group (e.g., benzyl and phenethyl), an aryl group (e.g., phenyl, pentafluorophenyl, 4-chlorophenyl, 3-nitrophenyl, 4-octylsulfamoylphenyl, and α-naphthyl), a heterocyclic group (e.g., pyridyl, thienyl, furyl, and imidazolyl), --NR 1  (R 2 ), --OR 3 , or --SR 4 . 
     R 1 , R 2 , R 3 , and R 4  may be the same or different and each represents an alkyl group, an aralkyl group, an aryl group, or a heterocyclic group. Examples of the alkyl group, the aralkyl group, the aryl group, and the heterocyclic group can be the same as those enumerated above for Z 1 . Note that each of R 1  and R 2  can be a hydrogen atom or an acyl group (e.g., acetyl, propanoyl, benzoyl, heptafluorobutanoyl, difluoroacetyl, 4-nitrobenzoyl, α-naphthoyl, and 4-trifluoromethylbenzoyl). 
     In Formula (IV), Z 1  preferably represents an alkyl group, an aryl group, or --NR 1  (R 2 ) and Z 2  preferably represents --NR 5  (R 6 ) wherein R 1 , R 2 , R 5 , and R 6  may be the same or different and each represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group. 
     More preferable examples of a selenium compound represented by Formula (IV) are N,N-dialkylselenourea, N,N,N&#39;-trialkyl-N&#39;-acylselenourea, tetraalkylselenourea, N,N-dialkyl-arylselenoamide, and N-alkyl-N-aryl-arylselenoamide. 
     Formula (V) ##STR5## wherein Z 3 , Z 4 , and Z 5  may be the same or different and each represents an aliphatic group, an aromatic group, a heterocyclic group, --OR 7 , --NR 8  (R 9 ), --SR 10 , --SeR 11 , X, or a hydrogen atom. 
     Each of R 7 , R 10 , and R 11  represents an aliphatic group, an aromatic group, a heterocyclic group, a hydrogen atom, or a cation, and each of R 8  and R 9  represents an aliphatic group, an aromatic group, a heterocyclic group, or a hydrogen atom. X represents a halogen atom. 
     In Formula (V), an aliphatic group represented by Z 3 , Z 4 , Z 5 , R 7 , R 8 , R 9 , R 10 , or R 11  represents a straight-chain, branched, or cyclic alkyl, alkenyl, alkynyl, or aralkyl group (e.g., methyl, ethyl, n-propyl, isopropyl, t-butyl, n-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopentyl, cyclohexyl, allyl, 2-butenyl, 3-pentenyl, propargyl, 3-pentynyl, benzyl, and phenethyl). 
     In Formula (V), an aromatic group represented by Z 3 , Z 4 , Z 5 , R 7 , R 8 , R 9 , R 10 , or R 11  represents a monocyclic or condensed-ring aryl group (e.g., phenyl, pentafluorophenyl, 4-chlorophenyl, 3-sulfophenyl, α-naphthyl, and 4-methylphenyl). 
     In Formula (V), a heterocyclic group represented by Z 3 , Z 4 , Z 5 , R 7 , R 8 , R 9 , R 10 , or R 11  represents a 3- to 10-membered saturated or unsaturated heterocyclic group (e.g., pyridyl, thienyl, furyl, thiazolyl, imidazolyl, and benzimidazolyl) containing at least one heteroatom selected from a nitrogen atom, an oxygen atom, and a sulfur atom. 
     In Formula (V), a cation represented by R 7 , R 10 , or R 11  represents an alkali metal atom or ammonium, and a halogen atom represented by X represents a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 
     In Formula (V), Z 3 , Z 4 , or Z 5  preferably represents an aliphatic group, an aromatic group, or --OR 7 , and R 7  preferably represents an aliphatic group or an aromatic group. 
     More preferable examples of a compound represented by Formula (V) are trialkylphosphineselenide, triarylphosphineselenide, trialkylselenophosphate, and triarylselenophosphate. 
     Practical examples of compounds represented by Formulas (IV) and (V) are presented below, but the present invention is not limited to these examples. ##STR6## 
     These selenium sensitizers are added in the form of a solution by dissolving in water, a solvent, such as methanol or ethanol, or a solvent mixture of these solvents, or in the form described in JP-A-4-140738 or JP-A-4-140739, so that they may be present during chemical sensitization. The selenium sensitizers are preferably added before start of chemical sensitization. A selenium sensitizer to be used is not limited to one type, but two or more of the selenium sensitizers described above can be used together. A combination of the labile selenium compound and the non-labile selenium compound may be used. 
     The addition amount of the selenium sensitizers used in the present invention varies depending on the activity of each selenium sensitizer used, the type or grain size of a silver halide, and the temperature and time of ripening. The addition amount, however, is preferably 1×10 -8  mole or more, and more preferably 1×10 -7  to 1×10 -5  mole per mole of a silver halide. When the selenium sensitizers are used, the temperature of chemical ripening is preferably 45° C. or more, and more preferably 50° C. to 80° C. The pAg and the pH can be set as desired. For example, the effect of the present invention can be obtained by a pH over a wide range of 4 to 9. 
     The selenium sensitization can be performed more effectively in the presence of a silver halide solvent. 
     Examples of the silver halide solvent usable in the present invention are (a) organic thioethers described in, e.g., U.S. Pat. Nos. 3,271,157, 3,531,289 and 3,574,628, JP-A-54-1019, and JP-A-54-158917, (b) thiourea derivatives described in, e.g., JP-A-53-82408, JP-A-55-77737, and JP-A-55-2982, (c) a silver halide solvent having a thiocarbonyl group sandwiched between an oxygen or sulfur atom and a nitrogen atom described in JP-A-53-144319, (d) imidazoles described in JP-A-54-100717, (e) a sulfite, and (f) a thiocyanate. 
     Most preferable examples of the silver halide solvent are thiocyanate and tetramethylthiourea. Although the amount of the solvent to be used varies depending on its type, a preferable amount of, e.g., thiocyanate is 1×10 -4  to 1×10 -2  mole per mole of a silver halide. 
     The silver halide photographic emulsion of the present invention can achieve a higher sensitivity and a lower fog when subjected to sulfur sensitization and/or gold sensitization, together with the selenium sensitization, in the chemical sensitization. 
     The sulfur sensitization is normally performed by adding sulfur sensitizers to an emulsion and stirring the resultant emulsion at a high temperature, preferably 40° C. or more for a predetermined time. 
     The gold sensitization is normally performed by adding gold sensitizers to an emulsion and stirring the emulsion at a high temperature, preferably 40° C. or more for a predetermined time. 
     Sulfur sensitizers known to those skilled in the art can be used in the sulfur sensitization. Examples of the sulfur sensitizer are thiosulfate, allylthiocarbamide, thiourea, allylisothiacyanate, cystine, p-toluenethiosulfonate, and rhodanine. It is also possible to use sulfur sensitizers described in, e.g., U.S. Pat. Nos. 1,574,944, 2,410,689, 2,278,947, 2,728,668, 3,501,313 and 3,656,955, German Patent 1,422,869, JP-B-56-24937, and JP-A-55-45016. The addition amount of the sulfur sensitizer need only be the one that can effectively increase the sensitivity of an emulsion. Although this amount varies over a wide range depending on various conditions, such as a pH, a temperature, and the size of silver halide grains, it is preferably 1×10 -7  to 5×10 -4  mole per mole of a silver halide. 
     The gold sensitizer for use in the gold sensitization can be any gold compound having an oxidation number of gold of +1 or +3, and it is possible to use gold compounds normally used as a gold sensitizer. Representative examples of the gold sensitizer are chloroaurate, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiacyanate, and pyridyltrichlorogold. 
     Although the addition amount of the gold sensitizer varies depending on various conditions, it is preferably 1×10 -7  and 5×10 -4  mole per mole of a silver halide. 
     In chemical ripening, it is not particularly necessary to limit the addition timings and the addition order of the silver halide solvent and the selenium sensitizers, or the sulfur and/or gold sensitizers usable in combination with the selenium sensitizers. For example, the above compounds can be added simultaneously or at different addition timings in (preferably) the initial stage of or during the chemical ripening. The above compounds are dissolved in water, an organic solvent miscible with water, such as methanol, ethanol, or acetone, or a solvent mixture of these solvents, and the resultant solution is added to an emulsion. 
     Emulsions of the present invention and other emulsions used together with the emulsions of the present invention will be described below. 
     The silver halide grain for use in the present invention consists of silver bromide, silver chloride, silver iodide, silver chlorobromide, silver iodochloride, silver bromoiodide, or silver bromochloroiodide. The silver halide grain may contain another silver salt, such as silver rhodanate, silver sulfide, silver selenide, silver carbonate, silver phosphate, or an organic acid silver, as another grain or as a portion of the grain. 
     The silver halide emulsion of the present invention preferably has a distribution or a structure associated with a halogen composition in its grains. A typical example of such a grain is a core-shell or double structure grain having different halogen compositions in its interior and surface layer as disclosed in, e.g., JP-B-43-13162, JP-A-61-215540, JP-A-60-222845, JP-A-60-143331, or JP-A-61-75337. The structure need not be a simple double structure but may be a triple structure or a multiple structure larger than the triple structure as disclosed in JP-A-60-222844. It is also possible to bond a thin silver halide having a different composition from that of a core-shell double-structure grain on the surface of the grain. 
     The structure to be formed inside a grain need not be the surrounding structure as described above but may be a so-called junctioned structure. Examples of the junctioned structure are disclosed in JP-A-59-133540, JP-A-58-108526, EP 199,290A2, JP-B-58-24772, and JP-A-59-16254. A crystal to be junctioned can be formed on the edge, the corner, or the face of a host crystal to have a different composition from that of the host crystal. Such a junctioned crystal can be formed regardless of whether a host crystal is uniform in halogen composition or has a core-shell structure. 
     In the case of the junctioned structure, it is naturally possible to use a combination of silver halides. However, it is also possible to form the junctioned structure by combining a silver halide and a silver salt compound not having a rock salt structure, such as silver rhodanate or silver carbonate. In addition, a non-silver salt compound, such as lead oxide, can also be used provided that formation of the junctioned structure is possible. 
     In a silver bromoiodide grain having any of the above structures, it is preferable that the silver iodide content in a core portion be higher than that in a shell portion. In contrast, it is sometimes preferable that the silver iodide content in the core portion be low and that in the shell portion be high. Similarly, in a junctioned-structure grain, the silver iodide content may be high in a host crystal and low in a junctioned crystal and vice versa. The boundary portion between different halogen compositions in a grain having any of the above structures may be either definite or indefinite. It is also possible to positively form a continuous composition change. 
     In a silver halide grain in which two or more silver halides are present as a mixed crystal or with a structure, it is important to control the distribution of halogen compositions between grains. A method of measuring the distribution of halogen compositions between grains is described in JP-A-60-254032. A uniform halogen distribution between grains is a desirable characteristic. In particular, a highly uniform emulsion having a variation coefficient of 20% or less is preferable. An emulsion having a correlation between a grain size and a halogen composition is also preferable. An example of the correlation is that larger grains have higher iodide contents and smaller grains have lower iodide contents. An opposite correlation or a correlation with respect to another halogen composition can also be selected in accordance with the intended use. For this purpose, it is preferable to mix two or more emulsions having different compositions. 
     It is important to control the halogen composition near the surface of a grain. Increasing the silver iodide content or the silver chloride content near the surface can be selected in accordance with the intended use because this changes a dye adsorbing property or a developing rate. In order to change the halogen composition near the surface, it is possible to use either the structure in which a grain is entirely surrounded by a silver halide or the structure in which a silver halide is adhered to only a portion of a grain. For example, a halogen composition of only one of a (100) face and a (111) face of a tetradecahedral grain may be changed, or a halogen composition of one of a major face or a side face of a tabular grain may be changed. 
     Silver halide grains for use in the emulsions of the present invention and emulsions to be used together with the emulsions of the present invention can be selected in accordance with the intended use. Examples are a regular crystal not containing a twin plane and crystals explained in Japan Photographic Society ed., The Basis of Photographic Engineering, Silver Salt Photography (CORONA PUBLISHING CO., LTD.), page 163, such as a single twinned crystal containing one twin plane, a parallel multiple twinned crystal containing two or more parallel twin planes, and a nonparallel multiple twinned crystal containing two or more nonparallel twin planes. A method of mixing grains having different shapes is disclosed in U.S. Pat. No. 4,865,964. So this method can be used as needed. In the case of a regular crystal, it is possible to use a cubic grain constituted by (100) faces, an octahedral grain constituted by (111) faces, or a dodecahedral grain constituted by (110) faces disclosed in JP-B-55-42737 or JP-A-60-222842. It is also possible to use, in accordance with the intended use of an emulsion, an (h11) face grain represented by a (211) face grain, an (hh1) face grain represented by a (331) face grain, an (hk 0) face grain represented by a (210) face grain, or an (hk1) face grain represented by a (321) face grain, as reported in Journal of Imaging Science, Vol. 30, page 247, 1986, although the preparation method requires some elaborations. A grain having two or more different faces, such as a tetradecahedral grain having both (100) and (111) faces, a grain having (100) and (110) faces, or a grain having (111) and (110) faces can also be used in accordance with the intended use of an emulsion. 
     A value obtained by dividing the equivalent-circle diameter of the projected area of a grain by the thickness of that grain is called an aspect ratio that defines the shape of a tabular grain. Tabular grains having aspect ratios higher than 1 can be used in the present invention. Tabular grains can be prepared by the methods described in, e.g., Cleve, Photography Theory and Practice (1930), page 131; Gutoff, Photographic Science and Engineering, Vol. 14, pages 248 to 257, (1970); and U.S. Pat. Nos. 4,434,226, 4,414,310, 4,433,048 and 4,439,520, and British Patent 2,112,157. The use of tabular grains brings about advantages, such as an increase in covering power and an increase in spectral sensitization efficiency due to sensitizing dyes. These advantages are described in detail in U.S. Pat. No. 4,434,226 cited above. An average aspect ratio of 80% or more of a total projected area of grains is preferably 1 to 100, more preferably 2 to 30, and most preferably 3 to 25.  The shape of a tabular grain can be selected from, e.g., a triangle, a hexagon, and a circle. An example of a preferable shape is a regular hexagon having six substantially equal sides, as described in U.S. Pat. No. 4,797,354. 
     The equivalent-circle diameter of the projected area is often used as the grain size of a tabular grain. Grains having an average diameter of 0.6 μm or less as described in U.S. Pat. No. 4,748,106 are preferable to improve an image quality. An emulsion having a narrow grain size distribution as described in U.S. Pat. No. 4,775,617 is also preferable. It is preferable to limit the grain thickness of a tabular grain to 0.5 μm to 0.05 μm, and more preferably 0.3 μm to 0.05 μm in increasing sharpness. An emulsion with a high uniformity in thickness, in which the variation coefficient of grain thicknesses is 30% to 3%, is also preferable. In addition, a grain in which a grain thickness and a distance between twin planes are defined, described in JP-A-63-163451, is preferable. 
     Dislocation lines of a tabular grain can be observed by using a transmission electron microscope. It is preferable to select a grain containing no dislocations, a grain containing several dislocation lines, or a grain containing a large number of dislocation lines in accordance with the intended use. It is also possible to select dislocation lines introduced linearly with respect to a specific direction of a crystal orientation of a grain or dislocation lines curved with respect to that direction. Alternatively, it is possible to selectively introduce dislocation lines throughout an entire grain or only to a particular portion of a grain, e.g., the fringe portion of a grain. Introduction of dislocation lines is preferable not only for tabular grains but for a regular crystal grain or an irregular grain represented by a potato-like grain. Also in this case, it is preferable to limit the positions of dislocation lines to specific portions, such as the corners or the edges, of a grain. 
     A silver halide emulsion used in the present invention may be subjected to a treatment for rounding grains, as disclosed in EP 96,727B1 or EP 64,412B1, or surface modification, as disclosed in West German Patent 2,306,447C2 or JP-A-60-221320. 
     Although a flat grain surface is common, intentionally forming projections and recesses on the surface is preferable in some cases. Examples are a methods described in JP-A-58-106532 and JP-A-60-221320, in which a hole is formed in a portion of a crystal, e.g., the corner or the center of the face of a crystal, and a ruffle grain described in U.S. Pat. No. 4,643,966. 
     The grain size of an emulsion used in the present invention can be evaluated in terms of the equivalent-circle diameter of the projected area of a grain obtained by using an electron microscope, the equivalent-sphere diameter of the volume of a grain calculated from the projected area and the thickness of the grain, or the equivalent-sphere diameter of the volume of a grain obtained by a Coulter counter method. It is possible to selectively use various grains from a very fine grain having an equivalent-sphere diameter of 0.05 μm or less to a large grain having that of 10 μm or more. It is preferable to use a grain having an equivalent-sphere diameter of 0.1 to 3 μm as a light-sensitive silver halide grain. 
     In the present invention, it is possible to use a so-called polydisperse emulsion having a wide grain size distribution or a monodisperse emulsion having a narrow grain size distribution in accordance with the intended use. As a measure representing the size distribution, a variation coefficient of either the equivalent-circle diameter of the projected area of a grain or the equivalent-sphere diameter of the volume of a grain is sometimes used when a monodisperse emulsion is to be used, it is desirable to use an emulsion having a size distribution with a variation coefficient of preferably 25% to 3%, more preferably 20% to 3%, and most preferably 15% to 3%. 
     The monodisperse emulsion is sometimes defined as an emulsion having a grain size distribution in which 80% or more of all grains fall within a range of ±30% of an average grain size represented by the number or the weight of grains. In order for a light-sensitive material to satisfy its target gradation, two or more monodisperse silver halide emulsions having different grain sizes can be mixed in the same emulsion layer or coated as different layers in an emulsion layer having essentially the same color sensitivity. It is also possible to mix, or coat as different layers, two or more types of polydisperse silver halide emulsions or monodisperse emulsions together with polydisperse emulsions. 
     Photographic emulsions used in the present invention can be prepared by the methods described in, e.g., P. Glafkides, Chimie et Physique Photographique, Paul Montel, 1967; G. F. Duffin, Photographic Emulsion Chemistry, Focal Press, 1966; and V. L. Zelikman et al., Making and Coating Photographic Emulsion, Focal Press, 1964. That is, any of an acid method, a neutral method, and an ammonia method can be used. In forming grains by a reaction of a soluble silver salt and a soluble halogen salt, any of a single-jet method, a double-jet method, and a combination of these methods can be used. It is also possible to use a method (so-called reverse double-jet method) of forming grains in the presence of excess silver ion. As one type of the double-jet method, a method in which the pAg of a liquid phase for producing a silver halide is maintained constant, i.e., a so-called controlled double-jet method can be used. This method makes it possible to obtain a silver halide emulsion in which a crystal shape is regular and a grain size is nearly uniform. 
     In some cases, it is preferable to make use of a method of adding silver halide grains already formed by precipitation to a reactor vessel for emulsion preparation, and the methods described in U.S. Pat. Nos. 4,334,012, 4,301,241, and 4,150,994. These silver halide grains can be used as seed crystal and are also effective when supplied as a silver halide for growth. In the latter case, addition of an emulsion with a small grain size is preferable. The total amount of an emulsion can be added at one time, or an emulsion can be separately added a plurality of times or added continuously. In addition, it is sometimes effective to add grains having several different halogen compositions in order to modify the surface. 
     A method of converting most of or only a part of the halogen composition of a silver halide grain by a halogen conversion process is disclosed in, e.g., U.S. Pat. Nos. 3,477,852 and 4,142,900, EP 273,429 and EP 273,430, and West German Patent 3,819,241. This method is an effective grain formation method. To convert into a silver salt that is more sparingly soluble, it is possible to add a solution of a soluble halogen salt or silver halide grains. The conversion can be performed at one time, separately a plurality of times, or continuously. 
     As a grain growth method other than the method of adding a soluble silver salt and a halogen salt at a constant concentration and a constant flow rate, it is preferable to use a grain formation method in which the concentration or the flow rate is changed, such as described in British Patent 1,469,480 and U.S. Pat. Nos. 3,650,757 and 4,242,445. Increasing the concentration or the flow rate can change the amount of a silver halide to be supplied as a linear function, a quadratic function, or a more complex function of the addition time. It is also preferable to decrease the silver halide amount to be supplied if necessary depending on the situation. Furthermore, when a plurality of soluble silver salts of different solution compositions are to be added or a plurality of soluble halogen salts of different solution compositions are to be added, a method of increasing one of the salts while decreasing the other is also effective. 
     A mixing vessel for reacting solutions of soluble silver salts and soluble halogen salts can be selected from those described in U.S. Pat. Nos. 2,996,287, 3,342,605, 3,415,650 and 3,785,777, and West German Patents 2,556,885 and 2,555,364. 
     A silver halide solvent is useful for the purpose of accelerating ripening. As an example, it is known to make an excess of halogen ions exist in a reactor vessel in order to accelerate ripening. Another ripening agent can also be used. The total amount of these ripening agents can be mixed in a dispersing medium placed in a reactor vessel before addition of silver and halide salts, or can be introduced to the reactor vessel simultaneously with addition of a halide salt, a silver salt, and a deflocculant. Alternatively, ripening agents can be independently added in the step of adding a halide salt and a silver salt. 
     Examples of the ripening agent are ammonia, thiocyanate (e.g., potassium rhodanate and ammonium rhodanate), an organic thioether compound (e.g., compounds described in U.S. Pat. Nos. 3,574,628, 3,021,215, 3,057,724, 3,038,805, 4,276,374, 4,297,439, 3,704,130 and 4,782,013, and JP-A-57-104926), a thione compound (e.g., tetra-substituted thioureas described in JP-A-53-82408, JP-A-55-77737, and U.S. Pat. No. 4,221,863, and compounds described in JP-A-53-144319), mercapto compounds capable of accelerating growth of silver halide grains, described in JP-A-57-202531, and an amine compound (e.g., JP-A-54-100717). 
     It is advantageous to use gelatin as a protective colloid for use in preparation of emulsions of the present invention or as a binder for other hydrophilic colloid layers. However, another hydrophilic colloid can also be used in place of gelatin. 
     Examples of the hydrophilic colloid are protein, such as a gelatin derivative, a graft polymer of gelatin and another high polymer, albumin, and casein; a cellulose derivative such as hydroxyethylcellulose, carboxymethylcellulose, and cellulose sulfates, a sugar derivative, such as sodium alginate, and a starch derivative; and a variety of synthetic hydrophilic high polymers, such as homopolymers or copolymers, e.g., polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, and polyvinyl pyrazole. 
     Examples of gelatin are lime-processed gelatin, acid-processed gelatin, and enzyme-processed gelatin described in Bull. Soc. Sci. Photo. Japan. No. 16, page 30 (1966). In addition, a hydrolyzed product or an enzyme-decomposed product of gelatin can also be used. 
     It is preferable to wash an emulsion used in the present invention for a desalting purpose and disperse it in a newly prepared protective colloid. Although the temperature of washing can be selected in accordance with the intended use, it is preferably 5° C. to 50° C. Although the pH at washing can also be selected in accordance with the intended use, it is preferably 2 to 10, and more preferably 3 to 8. The pAg at washing is preferably 5 to 10, though it can also be selected in accordance with the intended use. The washing method can be selected from noodle washing, dialysis using a semipermeable membrane, centrifugal separation, coagulation precipitation, and ion exchange. The coagulation precipitation can be selected from a method using sulfate, a method using an organic solvent, a method using a water-soluble polymer, and a method using a gelatin derivative. 
     In the preparation of an emulsion used in the present invention, it is preferable to make salt of metal ion exist during grain formation, desalting, or chemical sensitization, or before coating in accordance with the intended use. The metal ion salt is preferably added during grain formation in performing doping for grains, and after grain formation and before completion of chemical sensitization in modifying the grain surface or when used as a chemical sensitizer. The doping can be performed for any of an overall grain, only the core, the shell, or the epitaxial portion of a grain, and only a substrate grain. Examples of the metal are Mg, Ca, Sr, Ba, Al, Sc, Y, La, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ru, Rh, Pd, Re, Os, Ir, Pt, Au, Cd, Hg, Ti, In, Sn, Pb, and Bi. These metals can be added as long as they are in the form of a salt that can be dissolved during grain formation, such as ammonium salt, acetate, nitrate, sulfate, phosphate, hydroxide, 6-coordinated complex salt, or 4-coordinated complex salt. Examples are CdBr 2 , CdCl 2 , Cd(NO 3 ) 2 , Pb(NO 3 ).sub. 2, Pb(CH 3  COO) 2 , K 3  [Fe(CN) 6  ], (NH 4 ) 4  [Fe(CN) 6  ], K 3  IrCl 6 , (NH 4 ) 3  RhCl 6 , and K 4  Ru(CN) 6 . The ligand of a coordination compound can be selected from halo, aquo, cyano, cyanate, thiocyanate, nitrosyl, thionitrosyl, oxo, and carbonyl. These metal compounds can be used either singly or in a combination of two or more types of them. 
     The metal compounds are preferably dissolved in water or an appropriate organic solvent, such as methanol or acetone, and added in the form of a solution. To stabilize the solution, an aqueous hydrogen halide solution (e.g., HCl and HBr) or an alkali halide (e.g., KCl, NaCl, KBr, and NaBr) can be added. It is also possible to add acid or alkali if necessary. The metal compounds can be added to a reactor vessel either before or during grain formation. Alternatively, the metal compounds can be added to a water-soluble silver salt (e.g., AgNO 3 ) or an aqueous alkali halide solution (e.g., NaCl, KBr, and KI) and added in the form of a solution continuously during formation of silver halide grains. Furthermore, a solution of the metal compounds can be prepared independently of a water-soluble salt or an alkali halide and added continuously at a proper timing during grain formation. It is also possible to combine several different addition methods. 
     It is sometimes useful to perform a method of adding a chalcogen compound during preparation of an emulsion, such as described in U.S. Pat. No. 3,772,031. In addition to S, Se, and Te, cyanate, thiocyanate, selenocyanic acid, carbonate, phosphate, and acetate can be present. 
     Silver halide emulsions of the present invention are preferably subjected to reduction sensitization during grain formation, after grain formation and before or during chemical sensitization, or after chemical sensitization. 
     The reduction sensitization can be selected from a method of adding reduction sensitizers to a silver halide emulsion, a method called silver ripening in which grains are grown or ripened in a low-pAg environment at pAg 1 to 7, and a method called high-pH ripening in which grains are grown or ripened in a high-pH environment at pH 8 to 11. It is also possible to perform two or more of these methods together. 
     The method of adding reduction sensitizers is preferable in that the level of reduction sensitization can be finely adjusted. 
     Known examples of the reduction sensitizer are stannous chloride, ascorbic acid and its derivative, amines and polyamines, a hydrazine derivative, formamidinesulfinic acid, a silane compound, and a borane compound. In the reduction sensitization of the present invention, it is possible to selectively use these known reduction sensitizers or to use two or more types of compounds together. Preferable compounds as the reduction sensitizer are stannous chloride, thiourea dioxide, dimethylamineborane, and ascorbic acid and its derivative. Although an addition amount of the reduction sensitizers must be so selected as to meet the emulsion manufacturing conditions, a preferable amount is 10 -7  to 10 -3  mole per mole of a silver halide. 
     The reduction sensitizers are dissolved in water or an organic solvent, such as alcohols, glycols, ketones, esters, or amides, and the resultant solution is added during grain growth. Although adding to a reactor vessel in advance is also preferable, adding at a given timing during grain growth is more preferable. It is also possible to add the reduction sensitizers to an aqueous solution of a water-soluble silver salt or a water-soluble alkali halide to precipitate silver halide grains by using this aqueous solution. Alternatively, a solution of the reduction sensitizers may be added separately several times or continuously over a long time period with grain growth. 
     It is preferable to use an oxidizer for silver during the process of manufacturing emulsions used in the present invention. The oxidizer for silver means a compound having an effect of converting metal silver into silver ion. A particularly effective compound is the one that converts very fine silver grains, as a byproduct in the process of formation of silver halide grains and chemical sensitization, into silver ion. The silver ion produced may form a silver salt hardly soluble in water, such as a silver halide, silver sulfide, or silver selenide, or a silver salt readily soluble in water, such as silver nitrate. The oxidizer for silver may be either an inorganic or organic substance. Examples of the inorganic oxidizer are ozone, hydrogen peroxide and its adduct (e.g., NaBO 2  ·H 2  O 2  ·3H 2  O, 2NaCO 3  ·3H 2  O 2 , Na 4  P 2  O 7  ·2H 2  O 2 , and 2Na 2  SO 4  ·H 2  O 2  ·2H 2  O), peroxy acid salt (e.g., K 2  S 2  O 8 , K 2  C 2  O 6 , and K 2  P 2  O 8 ), a peroxy complex compound (e.g., K 2  [Ti(O 2 )C 2  O 4  ]·3H 2  O, 4K 2  SO 4  ·Ti(O 2 )OH·SO 4  ·2H 2  O, and Na 3  [VO(O 2 )(C 2  H 4 ) 2  ·6H 2  O), permanganate (e.g., KMnO 4 ), an oxyacid salt such as chromate (e.g., K 2  Cr 2  O 7 ), a halogen element such as iodine and bromine, perhalogenate (e.g., potassium periodate), a salt of a high-valence metal (e.g., potassium hexacyanoferrate(II)), and thiosulfonate. 
     Examples of the organic oxidizer are quinones such as p-quinone, an organic peroxide such as peracetic acid and perbenzoic acid, and a compound which releases active halogen (e.g., N-bromosuccinimide, chloramine T, and chloramine B). 
     Preferable oxidizers are an inorganic oxidizer such as ozone, hydrogen peroxide and its adduct, a halogen element, on a thiosulfonate, and an organic oxidizer such as quinones. A combination of the reduction sensitization described above and the oxidizer for silver is preferable. In this case, the reduction sensitization may be performed after the oxidizer is used or vice versa, or the reduction sensitization and the use of the oxidizer may be performed at the same time. These methods can be performed during grain formation or chemical sensitization. 
     Photographic emulsions used in the present invention may contain various compounds in order to prevent fog during the manufacturing process, storage, or photographic processing of a light-sensitive material, or to stabilize photographic properties. Usable compounds are those known as an antifoggant or a stabilizer, for example, thiazoles, such as benzothiazolium salt; nitroimidazoles; nitrobenzimidazoles; chlorobenzimidazoles; bromobenzimidazoles; mercaptothiazoles; mercaptobenzothiazoles; mecaptobenzimidazoles; mercaptothiadiazoles; aminotriazoles; benzotriazoles; nitrobenzotriazoles; mercaptotetrazoles (particularly 1-phenyl-5-mercaptotetrazole); mercaptopyrimidines; mercaptotriazines; a thioketo compound such as oxadolinethione; azaindenes, such as triazaindenes, tetrazaindenes (particularly hydroxy-substituted(1,3,3a,7)tetrazaindenes), and pentazaindenes. For example, compounds described in U.S. Pat. Nos. 3,954,474 and 3,982,947 and JP-B-52-28660 can be used. One preferable compound is described in JP-A-63-212932. Antifoggants and stabilizers can be added at any of several different timings, such as before, during, and after grain formation, during washing with water, during dispersion after the washing, before, during, and after chemical sensitization, and before coating, in accordance with the intended application. The antifoggants and the stabilizers can be added during preparation of an emulsion to achieve their original fog preventing effect and stabilizing effect. In addition, the antifoggants and the stabilizers can be used for various purposes of, e.g., controlling crystal habit of grains, decreasing a grain size, decreasing the solubility of grains, controlling chemical sensitization, and controlling an arrangement of dyes. 
     Photographic emulsions used in the present invention are preferably subjected to spectral sensitization by methine dyes and the like in order to achieve the effects of the present invention. Usable dyes involve a cyanine dye, a merocyanine dye, a composite cyanine dye, a composite merocyanine dye, a holopolar cyanine dye, a hemicyanine dye, a styryl dye, and a hemioxonole dye. Most useful dyes are those belonging to a cyanine dye, a merocyanine dye, and a composite merocyanine dye. Any nucleus commonly used as a basic heterocyclic nucleus in cyanine dyes can be contained in these dyes. Examples of a nucleus are a pyrroline nucleus, an oxazoline nucleus, a thiozoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus, and a pyridine nucleus; a nucleus in which an aliphatic hydrocarbon ring is fused to any of the above nuclei; and a nucleus in which an aromatic hydrocarbon ring is fused to any of the above nuclei, e.g., an indolenine nucleus, a benzindolenine nucleus, an indole nucleus, a benzoxadole nucleus, a naphthoxazole nucleus, a benzthiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus, and a quinoline nucleus. These nuclei may have a substituent on a carbon atom. 
     It is possible for a merocyanine dye or a composite merocyanine dye to have a 5- or 6-membered heterocyclic nucleus as a nucleus having a ketomethylene structure. Examples are a pyrazoline-5-one nucleus, a thiohydantoin nucleus, a 2-thiooxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus, and a thiobarbituric acid nucleus. 
     Although these sensitizing dyes may be used singly, they can also be used together. The combination of sensitizing dyes is often used for a supersensitization purpose. Representative examples of the combination are described in U.S. Pat. Nos. 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862 and 4,026,707, British Patents 1,344,281 and 1,507,803, JP-B-43-4936, JP-B-53-12375, JP-A-52-110618, and JP-A-52-109925. 
     Emulsions may contain, in addition to the sensitizing dyes, dyes having no spectral sensitizing effect or substances not essentially absorbing visible light and presenting supersensitization. 
     The sensitizing dyes can be added to an emulsion at any point in preparation of an emulsion, which is conventionally known to be useful. Most ordinarily, the addition is performed after completion of chemical sensitization and before coating. However, it is possible to perform the addition at the same timing as addition of chemical sensitizing dyes to perform spectral sensitization and chemical sensitization simultaneously, as described in U.S. Pat. Nos. 3,628,969 and 4,225,666. It is also possible to perform the addition prior to chemical sensitization, as described in JP-A-58-113928, or before completion of formation of a silver halide grain precipitation to start spectral sensitization. Alternatively, as disclosed in U.S. Pat. No. 4,225,666, these compounds can be added separately; a portion of the compounds may be added prior to chemical sensitization, while the remaining portion is added after that. That is, the compounds can be added at any timing during formation of silver halide grains, including the method disclosed in U.S. Pat. No. 4,183,756. 
     The addition amount may be 4×10 -6  to 8×10 -3  mole per mole of a silver halide. However, for a more preferable silver halide grain size of 0.2 to 1.2 μm, an addition amount of about 5×10 -5  to 2×10 -3  mole per mole of a silver halide is more effective. 
     Although the several different additives described above can be used in the light-sensitive material according to the present invention, a variety of other additives can also be used in accordance with the intended use. 
     The details of these additives are described in Research Disclosures Item 17643 (December, 1973), Item 18716 (November, 1979), and Item 308119 (December, 1989), and these portions are summarized in Table 1 below. 
     
                       TABLE 1                                                     
______________________________________                                    
     Additives     RD17643     RD18716                                    
______________________________________                                    
1.   Chemical      page 23     page 648, right                            
     sensitizers               column                                     
2.   Sensitivity               page 648, right                            
     increasing agent          column                                     
3.   Spectral      pages 23-24 page 648, right                            
     sensitizers,              column to page                             
     super                     649, right column                          
     sensitizers                                                          
4.   Brighteners   page 24                                                
5.   Antifoggants  pages 24-25 page 649, right                            
     and                       column                                     
     stabilizers                                                          
6.   Light         pages 25-26 page 649, right                            
     absorbent,                column to page                             
     filter dye,               650, left column                           
     ultraviolet                                                          
     absorbents                                                           
7.   Stain         page 25,    page 650, left to                          
     preventing    right column                                           
                               right columns                              
     agents                                                               
8.   dye image     page 25                                                
     stabilizer                                                           
9.   Hardening     page 26     page 651, left                             
     agents                    column                                     
10.  Binder        page 26     page 651, left                             
                               column                                     
11.  Plasticizers, page 27     page 650, right                            
     lubricants                column                                     
12.  Coating aids, pages 26-27 page 650, right                            
     surface                   column                                     
     active agents                                                        
13.  Antistatic    page 27     page 650, right                            
     agents                    column                                     
14.  Matting agents                                                       
______________________________________                                    
      Additives      RD308119                                             
______________________________________                                    
1.    Chemical       page 996                                             
      sensitizers                                                         
2.    Sensitivity                                                         
      increasing agents                                                   
3.    Spectral       page 996, right column                               
      sensitizers,   to page 998, right column                            
      super                                                               
      sensitizers                                                         
4.    Brighteners    page 998, right column                               
5.    Antifoggants   page 998, right column                               
      and            to page 1,000, right column                          
      stabilizers                                                         
6.    Light          pages 1,000, left column                             
      absorbent,     to page 1,0003, right column                         
      filter dye,                                                         
      ultraviolet                                                         
      absorbents                                                          
7.    Stain          page 1,002, right column                             
      preventing                                                          
      agents                                                              
8.    dye image      page 1,002, right column                             
      stabilizer                                                          
9.    Hardening      page 1,004, right column                             
      agents         to page 1,005, left column                           
10.   Binder         page 1,003, right column                             
                     to page 1,004, right column                          
11.   Plasticizers,  page 1,006, left to                                  
      lubricants     right column                                         
12.   Coating aids,  pages 1,005, left to                                 
      surface        right column                                         
      active agents                                                       
13.   Antistatic     page 1,006, right column                             
      agents         to page 1,007, left column                           
14.   Matting agents page 1,008, left column                              
                     to page 1,009, left column                           
______________________________________                                    
 
    
     In the light-sensitive material of the present invention, at least one of blue-, green-, and red-sensitive silver halide emulsion layers need only be formed on a support, and the number and order of the silver halide emulsion layers and non-light-sensitive layers are not particularly limited. A typical example is a silver halide photographic light-sensitive material having, on its support, at least one light-sensitive layer constituted by a plurality of silver halide emulsion layers which are sensitive to essentially the same color but have different sensitivities. This light-sensitive layer is a unit sensitive layer which is sensitive to one of blue light, green light, and red light. In a multilayered silver halide color photographic light-sensitive material, such unit light-sensitive layers are generally arranged in an order of red-, green-, and blue-sensitive layers from a support. However, according to the intended use, this arrangement order may be reversed, or light-sensitive layers sensitive to the same color may sandwich another light-sensitive layer sensitive to a different color. 
     Non-light-sensitive layers such as various types of interlayers may be formed between the silver halide light-sensitive layers and as the uppermost layer and the lowermost layer. 
     The interlayer may contain, e.g., couplers and DIR compounds as described in JP-A-61-43748, JP-A-59-113438, JP-A-59-113440, JP-A-61-20037, and JP-A-61-20038 or a color mixing inhibitor which is normally used. 
     As a plurality of silver halide emulsion layers constituting each unit light-sensitive layer, a two-layered structure of high- and low-speed emulsion layers can be preferably used as described in West German Patent 1,121,470 or British Patent 923,045. In this case, layers are preferably arranged such that the sensitivity is sequentially decreased toward a support, and a non-light-sensitive layer may be formed between the respective silver halide emulsion layers. In addition, as described in JP-A-57-112751, JP-A-62-200350, JP-A-62-206541, and JP-A-62-206543, layers may be arranged such that a low-speed emulsion layer is formed remotely from a support and a high-speed layer is formed close to the support. 
     More specifically, layers may be arranged from the farthest side from a support in an order of low-speed blue-sensitive layer (BL)/high-speed blue-sensitive layer (BH)/high-speed green-sensitive layer (GH)/low-speed green-sensitive layer (GL)/high-speed red-sensitive layer (RH)/low-speed red-sensitive layer (RL), an order of BH/BL/GL/GH/RH/RL, or an order of BH/BL/GH/GL/RL/RH. 
     In addition, as described in JP-B-55-34932, layers may be arranged from the farthest side from a support in an order of blue-sensitive layer/GH/RH/GL/RL. Furthermore, as described in JP-A-56-25738 and JP-A-62-63936, layers may be arranged from the farthest side from a support in an order of blue-sensitive layer/GL/RL/GH/RH. 
     As described in JP-B-49-15495, three layers may be arranged such that a silver halide emulsion layer having the highest sensitivity is arranged as an upper layer, a silver halide emulsion layer having sensitivity lower than that of the upper layer is arranged as an interlayer, and a silver halide emulsion layer having sensitivity lower than that of the interlayer is arranged as a lower layer, i.e., three layers having different sensitivities may be arranged such that the sensitivity is sequentially decreased toward the support. When a layer structure is constituted by three layers having different sensitivities, these layers may be arranged in an order of medium-speed emulsion layer/high-speed emulsion layer/low-speed emulsion layer from the farthest side from a support in a layer sensitive to one color as described in JP-A-59-202464. 
     In addition, an order of high-speed emulsion layer/low-speed emulsion layer/medium-speed emulsion layer or low-speed emulsion layer/medium-speed emulsion layer/high-speed emulsion layer may be adopted. 
     Furthermore, the arrangement can be changed as described above even when four or more layers are formed. 
     As described above, various layer arrangements and orders can be selectively used in accordance with the intended application of a light-sensitive material. 
     Known photographic additives usable in the present invention are also described in the above three Research Disclosures, and the corresponding portions are summarized in Table 2 below. 
     
                       TABLE 2                                                     
______________________________________                                    
                  RD17643      RD18716                                    
    Additives     [December, 1978]                                        
                               [November, 1979]                           
______________________________________                                    
1.  Chemical      page 23      page 648, right                            
    sensitizers                column                                     
2.  Sensitivity                page 648, right                            
    increasing agent           column                                     
3.  Spectral      pages 23-24  page 648, right                            
    sensitizers,               column to page                             
    super                      649, right column                          
    sensitizers                                                           
4.  Brighteners   page 24      page 647, right                            
                               column                                     
S.  Antifoggants  pages 24-25  page 649, right                            
    and                        column                                     
    stabilizers                                                           
6.  Light         pages 25-26  page 649, right                            
    absorbent,                 column to page                             
    filter dye,                650, left column                           
    ultraviolet                                                           
    absorbents                                                            
7.  Stain         page 25,     page 650, left to                          
    preventing    right column right columns                              
    agents                                                                
8.  dye image     page 25      page 650, left                             
    stabilizer                 column                                     
9.  Hardening     page 26      page 651, left                             
    agents                     column                                     
10. Binder        page 26      page 651, left                             
                               column                                     
11. Plasticizers, page 27      page 650, right                            
    lubricants                 column                                     
2.  Coating aids, pages 26-27  page 650, right                            
    surface                    column                                     
    active agents                                                         
3.  Antistatic    page 27      page 650, right                            
    agents                     column                                     
4.  Matting agents                                                        
______________________________________                                    
                        RD307105                                          
        Additives       [November, 1989]                                  
______________________________________                                    
1.      Chemical        page 866                                          
        sensitizers                                                       
2.      Sensitivity                                                       
        increasing agents                                                 
3.      Spectral        page 866-868                                      
        sensitizers,                                                      
        super                                                             
        sensitizers                                                       
4.      Brighteners     page 868                                          
5.      Antifoggants    pages 868-750                                     
        and                                                               
        stabilizers                                                       
6.      Light           page 873                                          
        absorbent,                                                        
        filter dye,                                                       
        ultraviolet                                                       
        absorbents                                                        
7.      Stain           page 872                                          
        preventing                                                        
        agents                                                            
8.      dye image       page 872                                          
        stabilizer                                                        
9.      Hardening       pages 874-875                                     
        agents                                                            
10.     Binder          pages 873-874                                     
11.     Plasticizers,   page 876                                          
        lubricants                                                        
12.     Coating aids,   pages 875-876                                     
        surface                                                           
        active agents                                                     
13.     Antistatic      pages 876-877                                     
        agents                                                            
14.     Matting agents  pages 878-879                                     
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     In addition, in order to prevent deterioration in photographic properties caused by formaldehyde gas, the light-sensitive material is preferably added with a compound described in U.S. Pat. No. 4,411,987 or U.S. Pat. No. 4,435,503, which can react with formaldehyde to fix it. 
     The light-sensitive material of the present invention preferably contains mercapto compounds described in U.S. Pat. Nos. 4,740,454 and 4,788,132, JP-A-62-18539, and JP-A-1-283551. 
     The light-sensitive material of the present invention preferably contains a compound described in JP-A-1-106052, which releases a fogging agent, a development accelerator, a silver halide solvent, or a precursor of any of them regardless of a developed amount of silver produced by development. 
     The light-sensitive material of the present invention preferably contains dyes dispersed by methods described in WO 04794/88 and PCT No. 1-502912, or dyes described in EP 317,308A, U.S. Pat. No. 4,420,555, and JP-A-1-259358. 
     Various color couplers can be used in the present invention, and specific examples of these couplers are described in patents described in above-mentioned Research Disclosure No. 17643, VII-C to VII-G and No. 307105, VII-C to VII-G. 
     Preferred examples of a yellow coupler are described in, e.g., U.S. Pat. Nos. 3,933,501, 4,022,620, 4,326,024, 4,401,752, and 4,248,961, JP-B-58-10739, British Patents 1,425,020 and 1,476,760, U.S. Pat. Nos. 3,973,968, 4,314,023, and 4,511,649, and EP 249,473A. 
     Examples of a magenta coupler are preferably 5-pyrazolone and pyrazoloazole compounds, and more preferably, compounds described in, e.g., U.S. Pat. Nos. 4,310,619 and 4,351,897, EP 73,636, U.S. Pat. Nos. 3,061,432 and 3,725,067, Research Disclosure No. 24220 (June 1984), JP-A-60-33552, Research Disclosure No. 24230 (June 1984), JP-A-60-43659, JP-A-61-72238, JP-A-60-35730, JP-A-55-118034, and JP-A-60-185951, U.S. Pat. Nos. 4,500,630, 4,540,654, and 4,565,630, and WO No. 88/04795. 
     Examples of a cyan coupler are phenol and naphthol couplers, and preferably, those described in, e.g., U.S. Pat. Nos. 4,052,212, 4,146,396, 4,228,233, 4,296,200, 2,369,929, 2,801,171, 2,772,162, 2,895,826, 3,772,002, 3,758,308, 4,343,011, and 4,327,173, West German Patent Application (OLS) No. 3,329,729, EP 121,365A and 249,453A, U.S. Pat. Nos. 3,446,622, 4,333,999, 4,775,616, 4,451,559, 4,427,767, 4,690,889, 4,254,212, and 4,296,199, and JP-A-61-42658. 
     Typical examples of a polymerized dye-forming coupler are described in U.S. Pat. Nos. 3,451,820, 4,080,221, 4,367,288, 4,409,320, and 4,576,910, British Patent 2,102,173, and EP 341,188A. 
     Preferable examples of a coupler capable of forming colored dyes having proper diffusibility are those described in U.S. Pat. No. 4,366,237, British Patent 2,125,570, EP 96,570, and West German Patent Application (OLS) No. 3,234,533. 
     Preferable examples of a colored coupler for correcting additional, undesirable absorption of a colored dye are those described in Research Disclosure No. 17643, VII-G and No. 307105, VII-G, U.S. Pat. No. 4,163,670, JP-B-57-39413, U.S. Pat. Nos. 4,004,929 and 4,138,258, and British Patent 1,146,368. A coupler for correcting unnecessary absorption of a colored dye by a fluorescent dye released upon coupling described in U.S. Pat. No. 4,774,181 or a coupler having a dye precursor group which can react with a developing agent to form a dye as a split-off group described in U.S. Pat. No. 4,777,120 may be preferably used. 
     Couplers releasing a photographically useful residue upon coupling are preferably used in the present invention. DIR couplers, i.e., couplers releasing a development inhibitor are described in the patents cited in the above-described RD No. 17643, VII-F, RD No. 307105, VII-F, JP-A-57-151944, JP-A-57-154234, JP-A-60-184248, JP-A-63-37346, JP-A-63-37350, and U.S. Pat. Nos. 4,248,962 and 4,782,012. 
     Preferable examples of a coupler for imagewise releasing a nucleating agent or a development accelerator are described in British Patents 2,097,140 and 2,131,188, JP-A-59-157638, and JP-A-59-170840. It is also preferable to use compounds described in JP-A-60-107029, JP-A-60-252340, JP-A-1-44940, and JP-A-1-45687, which release, e.g., a fogging agent, a development accelerator, or a silver halide solvent upon a redox reaction with an oxidized form of a developing agent. 
     Examples of a coupler which can be used in the light-sensitive material of the present invention are competing couplers described in, e.g., U.S. Pat. No. 4,130,427; poly-equivalent couplers described in, e.g., U.S. Pat. Nos. 4,283,472, 4,338,393, and 4,310,618; a DIR redox compound releasing coupler, a DIR coupler releasing coupler, a DIR coupler releasing redox compound, or a DIR redox releasing redox compound described in, e.g., JP-A-60-185950 and JP-A-62-24252; couplers releasing a dye which turns to a colored form after being released described in EP 173,302A and 313,308A; bleaching accelerator releasing couplers described in, e.g., RD. Nos. 11,449 and 24,241 and JP-A-61-201247; a ligand releasing coupler described in, e.g., U.S. Pat. No. 4,553,477; a coupler which releases a leuco dye described in JP-A-63-75747; and a coupler which releases a fluorescent dye described in U.S. Pat. No. 4,774,181. 
     The couplers for use in this invention can be added to the light-sensitive material by various known dispersion methods. 
     Examples of a high-boiling organic solvent to be used in the oil-in-water dispersion method are described in, e.g., U.S. Pat. No. 2,322,027. 
     Examples of a high-boiling organic solvent to be used in the oil-in-water dispersion method and having a boiling point of 175° C. or more at atmospheric pressure are phthalic esters (e.g., dibutylphthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decylphthalate, bis(2,4-di-t-amylphenyl)phthalate, bis(2,4-di-t-amylphenyl)isophthalate, and bis(1,1-di-ethylpropyl)phthalate), phosphates or phosphonates (e.g., triphenylphosphate, tricresylphosphate, 2-ethylhexyldiphenylphosphate, tricyclohexylphosphate, tri-2-ethylhexylphosphate, tridodecylphosphate, tributoxyethylphosphate, trichloropropylphosphate, and di-2-ethylhexylphenylphosphonate), benzoates (e.g., 2-ethylhexylbenzoate, dodecylbenzoate, and 2-ethylhexyl-p-hydroxybenzoate), amides (e.g., N,N-diethyldodecaneamide, N,N-diethyllaurylamide, and N-tetradecylpyrrolidone), alcohols or phenols (e.g., isostearylalcohol and 2,4-di-tert-amylphenol), aliphatic carboxylates (e.g., bis(2-ethylhexyl)sebacate, dioctylazelate, glyceroltributylate, isostearyllactate, and trioctylcitrate), an aniline derivative (e.g., N,N-dibutyl-2-butoxy-5-tert-octylaniline), and hydrocarbons (e.g., paraffin, dodecylbenzene, and diisopropylnaphthalene). An organic solvent having a boiling point of about 30° C. or more, and preferably, 50° C. to about 160° C. can be used as a co-solvent. Typical examples of the co-solvent are ethyl acetate, butyl acetate, ethyl propionate, methylethylketone, cyclohexanone, 2-ethoxyethylacetate, and dimethylformamide. 
     Steps and effects of a latex dispersion method and examples of an impregnating latex are described in, e.g., U.S. Pat. No. 4,199,363 and West German Patent Application (OLS) Nos. 2,541,274 and 2,541,230. 
     Various types of an antiseptic agent or a mildewproofing agent are preferably added to the color light-sensitive material of the present invention. Examples of the antiseptic agent and the mildewproofing agent are 1,2-benzisothiazoline-3-one, n-butyl-p-hydroxybenzoate, 2-phenoxyethanol, and 2-(4-thiazolyl)benzimidazole described in JP-A-63-257747, JP-A-62-272248, and JP-A-1-80941. 
     The present invention can be applied to various color light-sensitive materials. Examples of the material are a color negative film for a general purpose or a movie, a color reversal film for a slide or a television, color paper, a color positive film, and color reversal paper. The present invention can also be particularly preferably applied to a color duplicate film. 
     A support which can be suitably used in the present invention is described in, e.g., RD. No. 17643, page 28, RD. No. 18716, from the right column, page 647 to the left column, page 648, and RD. No. 307105, page 879. 
     In the light-sensitive material of the present invention, the total film thickness of all hydrophilic colloid layers on the side having emulsion layers is preferably 28 μm or less, more preferably 23 μm or less, particularly preferably 18 μm or less, and most preferably 16 μm or less. A film swell speed T 1/2  is preferably 30 sec. or less, and more preferably, 20 sec. or less. In this case, the film thickness means the thickness of a film measured under moisture conditioning at a temperature of 25° C. and a relative humidity of 55% (two days). The film swell speed T 1/2  can be measured in accordance with a known method in this field of art. For example, the film swell speed T 1/2  can be measured by using a swell meter described in Photogr. Sci Eng., A. Green et al., Vol. 19, No. 2, pp. 124 to 129. When 90% of a maximum swell film thickness reached by performing a treatment by using a color developing agent at 30° C. for 3 min. and 15 sec. is defined as a saturated film thickness, T 1/2  is defined as a time required for reaching 1/2 of the saturated film thickness. 
     The film swell speed T 1/2  can be adjusted by adding a film hardening agent to gelatin as a binder or changing aging conditions after coating. 
     In the light-sensitive material of the present invention, hydrophilic colloid layers (called back layers) having a total dried film thickness of 2 to 20 μm are preferably formed on the side opposite to the side having emulsion layers. The back layers preferably contain, e.g., the light absorbent, the filter dye, the ultraviolet absorbent, the antistatic agent, the film hardener, the binder, the plasticizer, the lubricant, the coating aid, and the surfactant described above. The swell ratio of the back layers is preferably 150% to 500%. 
     The color photographic light-sensitive material according to the present invention can be developed by conventional methods described in RD. No. 17643, pp. 28 and 29, RD. No. 18716, page 615, the left to right columns, and RD No. 307105, pp. 880 and 881. 
     A color developer used in development of the light-sensitive material of the present invention is preferably an aqueous alkaline solution mainly consisting of an aromatic primary amine-based color developing agent. As this color developing agent, although an aminophenol-based compound is effective, a p-phenylenediamine-based compound is preferably used. Typical examples of the p-phenylenediamine-based compound are 3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline, and sulfates, hydrochlorides and p-toluenesulfonates thereof. Of these compounds, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline sulfate is most preferred. These compounds can be used in a combination of two or more thereof in accordance with the application. 
     In general, the color developer contains a Ph buffering agent such as a carbonate, a borate, or a phosphate of an alkali metal, and a development restrainer or an antifoggant such as a bromide, an iodide, a benzimidazole, a benzothiazole, or a mercapto compound. If necessary, the color developer may also contain a preservative such as hydroxylamine, diethylhydroxylamine, a hydrazine sulfite, a phenylsemicarbazide, triethanolamine, or a catechol sulfonic acid; an organic solvent such as ethyleneglycol or diethyleneglycol; a development accelerator such as benzylalcohol, polyethyleneglycol, a quaternary ammonium salt or an amine; a dye forming coupler; a competing coupler; a fogging agent such as sodium boron hydride; an auxiliary developing agent such as 1-phenyl-3-pyrazolidone; a viscosity imparting agent; and a chelating agent such as aminopolycarboxylic acid, an aminopolyphosphonic acid, an alkylphosphonic acid, or a phosphonocarboxylic acid. Examples of the chelating agent are ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, hydroxyethyliminodiacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilo-N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N,N-tetramethylenephosphonic acid, and ethylenediamine-di(o-hydroxyphenylacetic acid), and salts thereof. 
     In order to perform reversal development, black-and-white development is performed and then color development is performed. As a black-and-white developer, well-known black-and-white developing agents, e.g., a dihydroxybenzene such as hydroquinone, a 3-pyrazolidone such as 1-phenyl-3-pyrazolidone, and an aminophenyl such as N-methyl-p-aminophenol can be used singly or in a combination of two or more thereof. 
     The pH of the color and black-and-white developers is generally 9 to 12. Although the quantity of replenisher of these developers depends on a color photographic light-sensitive material to be processed, it is generally 3 liters or less per m 2  of the light-sensitive material. The quantity of replenisher can be decreased to be 500 ml or less by decreasing a bromide ion concentration in the replenisher. In order to decrease the quantity of replenisher, a contact area of a processing tank with air is preferably decreased to prevent evaporation and oxidation of the replenisher upon contact with air. The quantity of replenisher can be decreased by using a means capable of suppressing an accumulation amount of bromide ions in the developer. 
     A contact area of a photographic processing solution with air in a processing tank can be represented by an aperture defined below: ##EQU1## 
     The above aperture is preferably 0.1 or less, and more preferably, 0.001 to 0.05. In order to reduce the aperture, a shielding member such as a floating cover may be provided on the liquid surface of the photographic processing solution in the processing tank. In addition, a method of using a movable cover described in JP-A-1-82033 or a slit developing method descried in JP-A-63-216050 may be used. The aperture is preferably reduced not only in color and black-and-white development steps but also in all subsequent steps, e.g., bleaching, bleach-fixing, fixing, washing, and stabilizing steps. In addition, a quantity of replenisher can be reduced by using a means of suppressing storage of bromide ions in the developing solution. 
     A color development time is normally two to five minutes. The processing time, however, can be shortened by setting a high temperature and a high pH and using the color developing agent at a high concentration. 
     The photographic emulsion layer is generally subjected to bleaching after color development. The bleaching may be performed either simultaneously with fixing (bleach-fixing) or independently thereof. In addition, in order to increase a processing speed, bleach-fixing may be performed after bleaching. Also, processing may be performed in a bleach-fixing bath having two continuous tanks, fixing may be performed before bleach-fixing, or bleaching may be performed after bleach-fixing, according to the intended use. Examples of the bleaching agent are a compound of a multivalent metal such as iron(III), peroxides, quinones, and a nitro compound. Typical examples of the bleaching agent are an organic complex salt of iron(III), e.g., a complex salt of an aminopolycarboxylic acid such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, methyliminodiacetic acid, and 1,3-diaminopropanetetraacetic acid, and glycoletherdiaminetetraacetic acid; or a complex salt of citric acid, tartaric acid, or malic acid. Of these compounds, an iron(III) complex salt of aminopolycarboxylic acid such as an iron(III) complex salt of ethylenediaminetetraacetic acid or 1,3-diaminopropanetetraacetic acid is preferred because it can increase a processing speed and prevent an environmental contamination. The iron(III) complex salt of aminopolycarboxylic acid is useful in both the bleaching and bleach-fixing solutions. The pH of the bleaching or bleach-fixing solution using the iron(III) complex salt of aminopolycarboxylic acid is normally 4.0 to 8. In order to increase the processing speed, however, processing can be performed at a lower pH. 
     A bleaching accelerator can be used in the bleaching solution, the bleach-fixing solution, and their pre-bath, if necessary. Useful examples of the bleaching accelerator are: compounds having a mercapto group or a disulfide group described in, e.g., U.S. Pat. No. 3,893,858, West German Patents 1,290,812 and 2,059,988, JP-A-53-32736, JP-A-53-57831, JP-A-53-37418, JP-A-53-72623, JP-A-53-95630, JP-A-53-104232, JP-A-53-124424, and JP-A-53-141623, and JP-A-53-28426, and Research Disclosure No. 17,129 (July, 1978); a thiazolidine derivative described in JP-A-50-140129; iodide salts described in JP-B-45-8506, JP-A-52-20832, JP-A-53-32735, U.S. Pat. No. 3,706,561, and JP-A-58-16235; polyoxyethylene compounds descried in West German Patents 977,410 and 2,748,430; a polyamine compound described in JP-B-45-8836; compounds descried in JP-A-49-40943, JP-A-49-59644, JP-A-53-94927, JP-A-54-35727, JP-A-55-26506, and JP-A-58-163940; and a bromide ion. Of these compounds, a compound having a mercapto group or a disulfide group is preferable since the compound has a large accelerating effect. In particular, compounds described in U.S. Pat. No. 3,893,858, West German Patent 1,290,812, and JP-A-53-95630 are preferred. A compound described in U.S. Pat. No. 4,552,834 is also preferable. These bleaching accelerators may be added in the light-sensitive material. These bleaching accelerators are useful especially in bleach-fixing of a photographic color light-sensitive material. 
     The bleaching solution or the bleach-fixing solution preferably contains, in addition to the above compounds, an organic acid in order to prevent a bleaching stain. The most preferable organic acid is a compound having an acid dissociation constant (pKa) of 2 to 5, for example, acetic acid, propionic acid, or hydroxyacetic acid. 
     Examples of the fixing agent are thiosulfate, a thiocyanate, a thioether-based compound, a thiourea and a large amount of an iodide. Of these compounds, a thiosulfate, especially, ammonium thiosulfate can be used in the widest range of applications. In addition, a combination of thiosulfate and a thiocyanate, a thioether-based compound, or thiourea is preferably used. As a preservative of the bleach-fixing solution, a sulfite, a bisulfite, a carbonyl bisulfite adduct, or a sulfinic acid compound described in EP 294,769A is preferred. In addition, in order to stabilize the fixing solution or the bleach-fixing solution, various types of aminopolycarboxylic acids or organic phosphonic acids are preferably added to the solution. 
     In the present invention, 0.1 to 10 mol/l of a compound having a pKa of 6.0 to 9.0 are preferably added to the fixing solution or the bleach-fixing solution in order to adjust the pH. Preferable examples of the compound are imidazoles such as imidazole, 1-methylimidazole, 1-ethylimidazole, and 2-methylimidazole. 
     The total time of a desilvering step is preferably as short as possible as long as no desilvering defect occurs. A preferable time is one to three minutes, and more preferably, one to two minutes. A processing temperature is 25° C. to 50° C., and preferably, 35° C. to 45° C. Within the preferable temperature range, a desilvering speed is increased, and generation of a stain after the processing can be effectively prevented. 
     In the desilvering step, stirring is preferably as strong as possible. Examples of a method of strengthening the stirring are a method of colliding a jet stream of the processing solution against the emulsion surface of the light-sensitive material described in JP-A-62-183460, a method of increasing the stirring effect using rotating means described in JP-A-62-183461, a method of moving the light-sensitive material while the emulsion surface is brought into contact with a wiper blade provided in the solution to cause disturbance on the emulsion surface, thereby improving the stirring effect, and a method of increasing the circulating flow amount in the overall processing solution. Such a stirring improving means is effective in any of the bleaching solution, the bleach-fixing solution, and the fixing solution. It is assumed that the improvement in stirring increases the speed of supply of the bleaching agent and the fixing agent into the emulsion film to lead to an increase in desilvering speed. The above stirring improving means is more effective when the bleaching accelerator is used, i.e., significantly increases the accelerating speed or eliminates fixing interference caused by the bleaching accelerator. 
     An automatic developing machine for processing the light-sensitive material of the present invention preferably has a light-sensitive material conveyor means described in JP-A-60-191257, JP-A-191258, or JP-A-60-191259. As described in JP-A-60-191257, this conveyor means can significantly reduce carry-over of a processing solution from a pre-bath to a post-bath, thereby effectively preventing degradation in performance of the processing solution. This effect significantly shortens especially a processing time in each processing step and reduces a processing solution replenishing amount. 
     The photographic light-sensitive material of the present invention is normally subjected to washing and/or stabilizing steps after desilvering. An amount of water used in the washing step can be arbitrarily determined over a broad range in accordance with the properties (e.g., a property determined by use of a coupler) of the light-sensitive material, the intended use of the material, the temperature of the water, the number of water tanks (the number of stages), a replenishing scheme representing a counter or forward current, and other conditions. The relationship between the amount of water and the number of water tanks in a multi-stage counter-current scheme can be obtained by a method described in &#34;Journal of the Society of Motion Picture and Television Engineering&#34;, Vol. 64, PP. 248-253 (May, 1955). 
     According to the above-described multi-stage counter-current scheme, the amount of water used for washing can be greatly decreased. Since washing water stays in the tanks for a long period of time, however, bacteria multiply and floating substances may be undesirably attached to the light-sensitive material. In order to solve this problem in the process of the color photographic light-sensitive material of the present invention, a method of decreasing calcium and magnesium ions can be effectively utilized, as described in JP-A-62-288838. In addition, a germicide such as an isothiazolone compound and cyabendazole described in JP-A-57-8542, a chlorine-based germicide such as chlorinated sodium isocyanurate, and germicides such as benzotriazole described in Hiroshi Horiguchi et al., &#34;Chemistry of Antibacterial and Antifungal Agents&#34;, (1986), Sankyo Shuppan, Eiseigijutsu-Kai ed., &#34;Sterilization, Antibacterial, and Antifungal Techniques for Microorganisms&#34;, (1982), Kogyogijutsu-Kai, and Nippon Bokin Bokabi Gakkai ed., &#34;Dictionary of Antibacterial and Antifungal Agents&#34;, (1986). 
     The pH of the water for washing the photographic light-sensitive material of the present invention is 4 to 9, and preferably, 5 to 8. The water temperature and the washing time can vary in accordance with the properties and the intended use of the light-sensitive material. Normally, the washing time is 20 seconds to minutes at a temperature of 15° C. to 45° C., and preferably, 30 seconds to 5 minutes at 25° C. to 40° C. The light-sensitive material of the present invention can be processed directly by a stabilizing agent in place of washing. All known methods described in JP-A-57-8543, JP-A-58-14834, and JP-A-60-220345 can be used in such stabilizing processing. 
     Stabilizing is sometimes performed subsequently to washing. An example is a stabilizing bath containing a dye stabilizing agent and a surface-active agent to be used as a final bath of the photographic color light-sensitive material. Examples of the dye stabilizing agent are an aldehyde such as formalin and glutaraldehyde, an N-methylol compound, hexamethylenetetramine, and an aldehyde sulfurous acid adduct. Various chelating agents or antifungal agents can be added in the stabilizing bath. 
     An overflow solution produced upon washing and/or replenishment of the stabilizing solution can be reused in another step such as a desilvering step. 
     In the processing using an automatic developing machine or the like, if each processing solution described above is condensed by evaporation, water is preferably added to correct condensation. 
     The silver halide color light-sensitive material of the present invention may contain a color developing agent in order to simplify processing and increases a processing speed. For this purpose, various types of precursors of a color developing agent can be preferably used. Examples of the precursor are an indoaniline-based compound described in U.S. Pat. No. 3,342,597, Schiff base compounds described in U.S. Pat. No. 3,342,599 and Research Disclosure (RD) Nos. 14,850 and 15,159, an aldol compound described in RD No. 13,924, a metal salt complex described in U.S. Pat. No. 3,719,492, and a urethane-based compound described in JP-A-53-135628. 
     The silver halide color light-sensitive material of the present invention may contain various 1-phenyl-3-pyrazolidones in order to accelerate color development, if necessary. Typical examples of the compound are described in JP-A-56-64339, JP-A-57-144547, and JP-A-58-115438. 
     Each processing solution in the present invention is used at a temperature of 10° C. to 50° C. Although a normal processing temperature is 33° C. to 38° C., processing may be accelerated at a higher temperature to shorten a processing time, or image quality or stability of a processing solution may be improved at a lower temperature. 
     The silver halide light-sensitive material of the present invention can be applied to thermal development light-sensitive materials described in, e.g., U.S. Pat. No. 4,500,626, JP-A-60-133449, JP-A-59-218443, JP-A-61-238056, and EP 210,660A2. 
     The silver halide color photographic light-sensitive material of the present invention can achieve its effects more easily when applied to film units with lenses described in JP-B-2-32615 and Published Examined Japanese Utility Model Application No. 3-39784. 
     The present invention will be described in greater detail below by way of its examples, but the invention is not limited to these examples. 
    
    
     EXAMPLE 1 
     Tabular Silver Bromoiodide Emulsion 
     (1) Preparation of Emulsions 
     &lt;Tabular silver bromoiodide core emulsion 1-A&gt; 
     While 1,200 cc of an aqueous solution containing 6.2 g Of gelatin and 6.4 g of KBr were stirred at 60° C., 8 cc of an aqueous 1.9M AgNO 3  solution and 9.6 cc of an aqueous 1.7M KBr solution were added to the solution by a double-jet method over 45 seconds. After 38 g of gelatin were added to the resultant solution, the solution was heated up to 75° C. and ripened in the presence of NH 3  for 20 minutes. The resultant solution was neutralized with HNO 3 , and 405 cc of an aqueous 1.9M AgNO 3  solution and an aqueous KBr solution containing 1 mol % of KI were added to the solution with the pAg kept at 8.22 while the flow rate was accelerated (such that the final flow rate was 10 times that at the beginning) over 87 minutes. Thereafter, the resultant emulsion was cooled to 35° C. and desalted by a regular flocculation process. The obtained silver bromoiodide emulsion consisted of tabular grains with an average equivalent-circle diameter of 2.0 μm, an average thickness of 0.25 μm, and an average aspect ratio of 8. 
     &lt;Tabular silver bromoiodide emulsion 1-B (Comparative emulsion)&gt; 
     The emulsion 1-A containing silver bromoiodide corresponding to 164 g of AgNO 3  was added to 1,950 cc of water, and the temperature, the pAg, and the pH of the resultant solution were kept at 55° C., 8.9, and 5.0, respectively. An aqueous 0.32M KI solution was added to the solution at a constant flow rate over one minute, and 206 cc of an aqueous 1.9M AgNO 3  solution and an aqueous 2.0M KBr solution were added to the resultant solution with the pAg kept at 8.9 over 36 minutes. Thereafter, the resultant emulsion was desalted by the conventional flocculation process. The obtained silver bromoiodide emulsion consisted of tabular grains with an average equivalent-circle diameter of 2.1 μm, an average thickness of 0.30 μm, and an average aspect ratio of 7. This was the same with emulsions 1-C to 1-H below. 
     &lt;Tabular silver bromoiodide emulsion 1-C (Comparative emulsion)&gt; 
     A tabular silver bromoiodide emulsion 1-C was prepared following the same procedures as for the emulsion 1-B except for the following. 
     A silver iodide fine grain emulsion having an average grain size of 0.02 μm and corresponding to 6.8 g of AgNO 3  was prepared beforehand, was added to the solution instead of the addition of the aqueous KI solution and was completely dissolved during 10 minutes. 
     &lt;Tabular silver bromoiodide emulsion 1-D (comparative emulsion&gt; 
     A comparative emulsion 1-D was prepared following the same procedures as for the emulsion 1-B, except that an aqueous iodoacetic acid (7.5 g) solution was added in place of the aqueous KI solution, the pH was raised to 10.5, maintained at that value for 15 minutes, and then decreased to 5.0 after iodide ions were released slowly. 
     &lt;Tabular silver bromoiodide emulsion 1-E (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 1-E was prepared following the same procedures as for the emulsion 1-B except the following. 
     After 2-iodoethanol (3.1 cc) was added to the solution instead of the addition of the aqueous KI solution, the pH was raised to 9.5 by adding an aqueous NaOH solution. The pH was kept at that value for 10 minutes and then returned to 5.0 after iodide ions were rapidly generated. 
     &lt;Tabular silver bromoiodide emulsion 1-F (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 1-F was prepared following the same procedures as for the emulsion 1-E except the following. 
     After 2-iodoethanol (3.1 cc) was added to the solution, the pH was raised to 10.5 by adding an aqueous NaOH solution. The pH was kept at that value for 4 minutes and then returned to 5.0 after iodide ions were rapidly generated. 
     &lt;Tabular silver bromoiodide emulsion 1-G (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 1-G was prepared following the same procedures as for the emulsion 1-B except the following. 
     The temperature was kept at 40° C. instead of 55° C. 
     After sodium p-iodoacetamidobenzenesulfonate (15.3 g) was added to the solution instead of the addition of the aqueous KI solution, an aqueous 0.80M sodium sulfite solution (75 cc) was added, and the pH was raised to 9.0 by adding an aqueous NaOH solution. The pH was kept at that value for 10 minutes and then returned to 5.0 after iodide ions were rapidly generated. 
     &lt;Tabular silver bromoiodide emulsion 1-H (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 1-H was prepared following the same procedures as for the emulsion 1-B except the following. 
     After sodium p-iodoacetamidobenzenesulfonate (15.3 g) was added to the solution instead of the addition of the aqueous KI solution, an aqueous 0.80M sodium sulfite solution (60 cc) was added, and the pH was raised to 9.0 by adding an aqueous NaOH solution. The pH was kept at that value for 8 minutes and then returned to 5.0 after iodide ions were rapidly generated. 
     &lt;Tabular silver bromoiodide emulsion 1-I (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 1-I was prepared following the same procedures as for the emulsion 1-G except the following. The temperature was kept at 55° C. instead of 40° C. 
     &lt;Tabular silver bromoiodide core emulsion 2-A&gt; 
     A tabular silver bromoiodide core emulsion 2-A was prepared following the same procedures as for the emulsion 1-A except the following. The temperature was kept at 30° C. instead of 60° C. Instead of the addition of 8 cc of the aqueous 1.9M AgNO 3  solution and 9.6 cc of the aqueous 1.7M KBr solution over 45 seconds, 48 cc of an aqueous 0.1M AgNO 3  solution and 25 cc of an aqueous 0.2M KBr solution were added over 10 seconds. Thereafter, instead of the ripening in the presence of NH 3 , physical ripening was performed in the absence of NH 3  for 20 minutes. The resultant silver bromoiodide emulsion consisted of tabular grains with an average equivalent-circle diameter of 2.6 μm, an average thickness of 0.14 μm, and an average aspect ratio of 19. 
     &lt;Tabular silver bromoiodide emulsion 2-B (Comparative emulsion)&gt; 
     A tabular silver bromoiodide emulsion 2-B was prepared following the same procedures as for the emulsion 1-B except the following. The emulsion 2-A was used in place of the emulsion 1-A. The resultant silver bromoiodide emulsion consisted of tabular grains with an average equivalent-circle diameter of 2.7 μm, an average thickness of 0.18 μm, and an average aspect ratio of 15. This was the same with an emulsion 2-C below. 
     &lt;Tabular silver bromoiodide emulsion 2-C (Emulsion of present invention)&gt; 
     A tabular silver bromoiodide emulsion 2-C was prepared following the same procedures as for the emulsion 1-I except the following. The emulsion 2-A was used in place of the emulsion 1-A. 
     (2) Chemical Sensitization 
     Gold-sulfur sensitization was performed for the emulsions 1-B to 1-I, 2-B, and 2-C as follows. 
     Each emulsion was heated up to 64° C. and subjected to optimal chemical sensitization by adding 2.4×10 -4  mole/moleAg, 1.0×10 -5  mole/moleAg, and 3.5×10 -4  mole/moleAg of sensitizing dyes ExS-1, ExS-2, and ExS-3 (to be presented later), respectively, and also adding 9.0×10 -6  mole/moleAg of sodium thiosulfate, 1.9×10 -3  mole/moleAg of potassium thiocyanate, and 1.0×10 -6  mole/moleAg of chloroauric acid. The &#34;optimal chemical sensitization&#34; means chemical sensitization by which a highest sensitivity is obtained when exposure is performed for 1/100 second. 
     Gold-sulfur-selenium sensitization was performed for the emulsions 1-B to 1-I, 2-B, and 2-C as follows. 
     Each emulsion was heated up to 64° C. and subjected to optimal chemical sensitization by adding 2.4×10 -4  mole/moleAg, 1.0×10 -5  mole/moleAg, and 3.5×10 -4  mole/moleAg of the sensitizing dyes ExS-1, ExS-2, and ExS-3 (to be presented later), respectively, and also adding 7.4×10 -6  mole/moleAg of sodium thiosulfate, 1.9×10 -6  mole/moleAg of chloroauric acid, 1.9×10 -3  mole/moleAg of potassium thiocyanate, and 1.5×10 -6  mole/moleAg of N,N-dimethylselenourea. 
     (3) Making and Evaluation of Coated Samples Emulsion and protective layers were coated in amounts as shown in Table 3 below on cellulose triacerate film supports with subbing layers, thereby making coated samples 1 to 20. 
     
                       TABLE 3                                                     
______________________________________                                    
Emulsion coating conditions                                               
______________________________________                                    
(1) Emulsion layer                                                        
    Emulsion . . . each emulsion                                          
                      (silver 3.6 × 10.sup.-2 mole/m.sup.2)         
    Coupler represented by the                                            
                      (1.5 × 10.sup.-3 mole/m.sup.2)                
    formula below                                                         
 ##STR7##                                                                 
    Tricresylphosphate                                                    
                      (1.10 g/m.sup.2)                                    
    Gelatin           (2.30 g/m.sup.2)                                    
(2) Protective layer                                                      
    2,4-dichloro-6-hydroxy-s-                                             
                      (0.08 g/m.sup.2)                                    
    triazine sodium salt                                                  
    Gelatin           (1.80 g/m.sup.2)                                    
______________________________________                                    
 
    
     These samples were left to stand at a temperature of 40° C. and a relative humidity of 70% for 14 hours, exposed through a continuous wedge for 1/100 second, and subjected to color development shown in Table 4 below. 
     The densities of the samples thus processed were measured through a green filter. 
     
                       TABLE 4                                                     
______________________________________                                    
Process        Time       Temperature                                     
______________________________________                                    
Color development                                                         
               2 min. 00 sec.                                             
                          40° C.                                   
Bleach-fixing  2 min. 00 sec.                                             
                          40° C.                                   
Washing (1)    20 sec.    35° C.                                   
Washing (2)    20 sec.    35° C.                                   
Stabilization  20 sec.    35° C.                                   
Drying         50 sec.    65° C.                                   
______________________________________                                    
 
    
     The compositions of the individual processing solutions are given below. 
     
         ______________________________________                                    
(Color developing solution)     (g)                                       
Diethylenetriaminepentaacetic acid                                        
                       2.0                                                
1-hydroxyethylidene-1,1-                                                  
                       3.0                                                
diphosphonic acid                                                         
Sodium sulfite         4.0                                                
Potassium carbonate    30.0                                               
Potassium bromide      1.4                                                
Potassium iodide       1.5      mg                                        
Hydroxylamine sulfate  2.4                                                
4-[N-ethyl-N-β-hydroxylethylamino]-                                  
                       4.5                                                
2-methylaniline sulfate                                                   
Water to make          1.0      l                                         
pH                     10.05                                              
(Bleach-fixing solution)        (g)                                       
Ferric ammonium ethylenediamine-                                          
                       90.0                                               
tetraacetate dihydrate                                                    
Sodium ethylenediaminetetraacetate                                        
                       5.0                                                
Sodium sulfite         12.0                                               
Ammonium thiosulfate   260.0    ml                                        
aqueous solution (70%)                                                    
Acetic acid (98%)      5.0      ml                                        
Bleaching accelerator shown below                                         
                       0.01     mole                                      
 ##STR8##                                                                 
Water to make          1.0      l                                         
pH                     6.0                                                
______________________________________                                    
 
    
     (Washing solution) 
     Tap water was supplied to a mixed-bed column filled with an H type cation exchange resin (Amberlite IR-120B: available from Rohm &amp; Haas Co.) and an OH type anion exchange resin (Amberlite IR-400) to set the concentrations of calcium and magnesium to be 3 mg/l or less. Subsequently, 20 mg/l of sodium isocyanurate dichloride and 1.5 g/l of sodium sulfate were added. 
     The pH of the solution ranged from 6.5 to 7.5. 
     
         ______________________________________                                    
(Stabilizing solution)     (g)                                            
______________________________________                                    
Formalin (37%)             2.0 ml                                         
Polyoxyethylene-p-monononylphenylether                                    
                           0.3                                            
(average polymerization degree = 10)                                      
Disodium ethylenediaminetetraacetate                                      
                           0.05                                           
Water to make              1.0 l                                          
pH                         5.0-8.0                                        
______________________________________                                    
 
    
     The sensitivity is represented by a relative value of the logarithm of the reciprocal of an exposure amount (lux.sec) at which a density of fog+0.2 is given. The gamma was obtained as the slope of a straight line connecting a point of fog+0.2 and a point of fog+1.2. The obtained results are summarized in Table 5 below. 
     
         TABLE 5
     Iodide  Temperature          ion pH during during Time required for
   release release of release 50% of iodide ion Sample  Iodide ion supply
 controlling iodide of iodide source to release Chemical No. Emulsion
 source agent ions ions iodide ions sensitization Sensitivity Gamma Fog
 Remarks
   1 1-B KI None 5.0 55(°C.) -- S 100 100 0.23 Comparative
    example 2 &#34; &#34; &#34; &#34; &#34; -- Se 120  85 0.51 Comparative            example
 3 1-C AgI fine grain &#34; &#34; &#34; 5 min. S  95  99 0.25 Comparative   (0.02
 μm)         example 4 &#34; AgI fine grain &#34; &#34; &#34; &#34; Se 117  84 0.52
 Comparative   (0.02 μm)         example 5 1-D ICH.sub.2 COOH NaOH
 5.0-10.5 &#34; 30 min. or more *1 S  93  90 0.30 Comparative
 example 6 &#34; &#34; &#34; &#34; &#34; &#34; Se 105  72 0.59 Comparative            example 7
 1-E ICH.sub.2 CH.sub.2
  OH &#34; 5.0-9.5 &#34; 120 sec *1 S 107 101 0.19 Comparative            example
 8 &#34; &#34; &#34; &#34; &#34; &#34; Se 138 104 0.17 Invention 9 1-F &#34; &#34;  5.0-10.0 &#34; 30 sec *1
 S 110 103 0.18 Comparison 10 &#34; &#34; &#34; &#34; &#34; &#34; Se 141 105 0.16 Invention  11
 1-G
  ##STR9##
  Na.sub.2 SO.sub.3 5.0-9.0 40(°C.) 50 sec *1 S 110 103 0.20
  ComparisonInvention  12 &#34; &#34; &#34; &#34; &#34; 50 sec *1 Se 141 106 0.18 Invention
 13 1-H &#34; &#34; &#34; 55(°C.) 10 sec *1 S 112 104 0.19 Comparison 14 &#34; &#34; &#34;
 &#34; &#34; &#34; Se 145 106 0.18 Invention 15 1-I &#34; &#34; &#34; &#34; 5 sec *1 S 115 104 0.18
 Comparison 16 &#34; &#34; &#34; &#34; &#34; &#34; Se 148 106 0.17 Invention 17 2-B KI None 5.0 &#34;
 -- S 105 102 0.30 Compartive            example 18 &#34; &#34; &#34; &#34; &#34; -- Se 123
 107 0.52 Compartive            example
  19 2-C
 ##STR10##
  Na.sub.2 SO.sub.3 5.0-9.0 &#34; 5 sec *1 S 148 106 0.25 Compartiveexample
 20 &#34; &#34; &#34; &#34; &#34; &#34; Se 158 110 0.25 Invention
 *1: Measured from the changes in the amount of iodide ionreleasing agent
 contained in the solution from which emulsion grains have been separated
 by centrifugal separation, said amount having been determined by ICP
 (Inductively Coupled PlasamEmission) analysis. (The rate of iodide ion
 release was determined, starting at the moment the pH was raised to 10.5
 for the emulsion 1D and 1F, to 9.5 for the emulsions 1E, and to 9.0 for
 the emulsions 1G to 1I and 2C).
 The sensitivity and the gamma were represented by a relative value
 assuming that the sample 1 is 100.
 S and Se in the chemical sensitization are respectively indicated in a
 GoldSulfur sensitization and a Goldsulfur-Selenium sensitization.
 
    
     As is apparent from Table 5, according to the present invention, an emulsion having a low fog, a high sensitivity, and a large gamma value could be obtained. 
     EXAMPLE 2 
     Gold-sulfur-selenium sensitization was performed for the emulsions 1-B, 1-H, 1-J, and 1-K prepared in Example 1 as follows. 
     Each emulsion was heated up to 64° C. and subjected to optimal chemical sensitization by adding 4.7×10 -5  mole/moleAg, 1.1×10 -4  mole/moleAg, and 4.0×10 -4  mole/moleAg of sensitizing dyes ExS-4, ExS-5, and ExS-6 (to be presented later), respectively, and also adding 7.4×10 -6  mole/moleAg of sodium thiosulfate, 1.9×10 -3  mole/moleAg of potassium thiocyanate, 1.9×10 -6  mole/moleAg of chloroauric acid, and 2.3×10 -6  mole/moleAg of N,N-dimethylselenourea. 
     Layers having the compositions presented below were coated on subbed triacetylcellulose film supports to make samples 101 to 104 as multilayered color light-sensitive materials. 
     (Compositions of light-sensitive layers) 
     The main materials used in the individual layers are classified as follows. 
     
         ______________________________________                                    
ExC:  Cyan coupler UV:     Ultraviolet absorbent                          
ExM:  Magenta coupler                                                     
                   HBS:    High-boiling organic solvent                   
ExY:  Yellow coupler                                                      
                   H:      Gelatin hardener                               
ExS:  Sensitizing dye                                                     
______________________________________                                    
 
    
     The number corresponding to each component indicates the coating amount in units of g/m 2 . The coating amount of a silver halide is represented by the amount of silver. The coating amount of each sensitizing dye is represented in units of mols per mol of a silver halide in the same layer. 
     (Samples 101-104) 
     
         ______________________________________                                    
1st layer (Antihalation layer)                                            
Black colloidal silver     silver 0.18                                    
Gelatin                    1.40                                           
ExM-1                      0.18                                           
ExF-1                      2.0 × 10.sup.-3                          
2nd layer (Interlayer)                                                    
Emulsion G                 silver 0.065                                   
2,5-di-t-pentadecylhydroquinone                                           
                           0.18                                           
ExC-2                      0.020                                          
UV-1                       0.060                                          
UV-2                       0.080                                          
UV-3                       0.10                                           
HBS-1                      0.10                                           
HBS-2                      0.020                                          
Gelatin                    1.04                                           
3rd layer (Low-speed red-sensitive emulsion layer)                        
Emulsion A                 silver 0.25                                    
Emulsion B                 silver 0.25                                    
ExS-1                      6.9 × 10.sup.-5                          
ExS-2                      1.8 × 10.sup.-5                          
ExS-3                      3.1 × 10.sup.-4                          
ExC-1                      0.17                                           
ExC-4                      0.17                                           
ExC-7                      0.020                                          
UV-1                       0.070                                          
UV-2                       0.050                                          
UV-3                       0.070                                          
HBS-1                      0.060                                          
Gelatin                    0.87                                           
4th layer                                                                 
(medium-speed red-sensitive emulsion layer)                               
Emulsion D                 silver 0.80                                    
ExS-1                      3.5 × 10.sup.-4                          
ExS-2                      1.6 × 10.sup.-5                          
ExS-3                      5.1 × 10.sup.-4                          
ExC-1                      0.20                                           
ExC-2                      0.050                                          
ExC-4                      0.20                                           
ExC-5                      0.050                                          
ExC-7                      0.015                                          
UV-1                       0.070                                          
UV-2                       0.050                                          
UV-3                       0.070                                          
Gelatin                    1.30                                           
5th layer (High-speed red-sensitive emulsion layer)                       
Emulsion E                 silver 1.40                                    
ExS-1                      2.4 × 10.sup.-4                          
ExS-2                      1.0 × 10.sup.-4                          
ExS-3                      3.4 × 10.sup.-4                          
ExC-1                      0.097                                          
ExC-2                      0.010                                          
ExC-3                      0.065                                          
ExC-6                      0.020                                          
HBS-1                      0.22                                           
HBS-2                      0.10                                           
Gelatin                    1.63                                           
6th layer (Interlayer)                                                    
Cpd-1                      0.040                                          
HBS-1                      0.020                                          
Gelatin                    0.80                                           
7th layer (Low-speed green-sensitive emulsion layer)                      
Emulsion C                 silver 0.30                                    
ExS-4                      2.6 × 10.sup.-5                          
ExS-5                      1.8 × 10.sup.-4                          
ExS-6                      6.9 × 10.sup.-4                          
ExM-1                      0.021                                          
ExM-2                      0.26                                           
ExM-3                      0.030                                          
ExY-1                      0.025                                          
HBS-1                      0.10                                           
HBS-3                      0.010                                          
Gelatin                    0.63                                           
8th layer                                                                 
(Medium-speed green-sensitive emulsion layer)                             
Emulsion D                 silver 0.55                                    
ExS-4                      2.2 × 10.sup.-5                          
ExS-5                      1.5 × 10.sup.-4                          
ExS-6                      5.8 × 10.sup.-4                          
ExM-2                      0.094                                          
ExM-3                      0.026                                          
ExY-1                      0.018                                          
HBS-1                      0.16                                           
HBS-3                      8.0 × 10.sup.-3                          
Gelatin                    0.50                                           
9th layer (High-speed green-sensitive emulsion layer)                     
Emulsion (emulsion 2-B, 1-I, 2-B, or 2-C)                                 
                           silver 1.55                                    
ExC-1                      0.015                                          
ExM-1                      0.013                                          
ExM-4                      0.065                                          
ExM-5                      0.019                                          
HBS-1                      0.25                                           
HBS-2                      0.10                                           
Gelatin                    1.54                                           
10th layer (Yellow filter layer)                                          
Yellow colloidal silver    silver 0.035                                   
Cpd-1                      0.080                                          
HBS-1                      0.030                                          
Gelatin                    0.95                                           
11th layer (Low-speed blue-sensitive emulsion layer)                      
Emulsion C                 silver 0.18                                    
ExS-7                      8.0 × 10.sup.-4                          
ExY-1                      0.042                                          
ExY-2                      0.72                                           
HBS-1                      0.28                                           
Gelatin                    1.10                                           
12th layer                                                                
(Medium-speed blue-sensitive emulsion layer)                              
Emulsion D                 silver 0.40                                    
ExS-7                      7.4 × 10.sup.-4                          
ExC-7                      7.0 × 10.sup.- 3                         
ExY-2                      0.15                                           
HBS-1                      0.050                                          
Gelatin                    0.78                                           
13th layer (High-speed blue-sensitive emulsion layer)                     
Emulsion F                 silver 0.70                                    
ExS-7                      2.8 × 10.sup.-4                          
ExY-2                      0.20                                           
HBS-1                      0.070                                          
Gelatin                    0.69                                           
14th layer (1st protective layer)                                         
Emulsion G                 silver 0.20                                    
UV-4                       0.11                                           
UV-5                       0.17                                           
HBS-1                      5.0 × 10.sup.-2                          
Gelatin                    1.00                                           
15th layer (2nd protective layer)                                         
H-1                        0.40                                           
B-1 (diameter 1.7 μm)   5.0 × 10.sup.-2                          
B-2 (diameter 1.7 μm)   0.10                                           
B-3                        0.10                                           
S-1                        0.20                                           
Gelatin                    1.20                                           
______________________________________                                    
 
    
     In addition to the above components, to improve storage stability, processability, a resistance to pressure, antiseptic and mildewproofing properties, antistatic properties, and coating properties, the individual layers contained W-1 to W-3, B-4 to B-6, F-1 to F-17, iron salt, lead salt, gold salt, platinum salt, iridium salt, and rhodium salt. The emulsions A to G are listed in Table 6 below and the formulas of the compounds used are given below. 
     
                                           TABLE 6                                 
__________________________________________________________________________
               Variation                                                  
Average   Average                                                         
               coefficient  Silver amount ratio                           
AgI       grain                                                           
               (%) accord-                                                
                      Diameter/                                           
                            [core/intermediate/                           
content   size ing to thickness                                           
                            shell]    Grain                               
(%)       (μm)                                                         
               grain size                                                 
                      ratio (AgI content)                                 
                                      structure/shape                     
__________________________________________________________________________
Emulsion                                                                  
     4.0  0.45 27     1     [1/3] (13/1)                                  
                                      Double                              
A                                     structure                           
                                      octahedral grain                    
Emulsion                                                                  
     8.9  0.70 14     1     [3/7] (25/2)                                  
                                      Double                              
B                                     structure                           
                                      octahedral grain                    
Emulsion                                                                  
     2.0  0.55 25     7     --        Uniform                             
C                                     structure                           
                                      tabular grain                       
Emulsion                                                                  
     9.0  0.65 25     6     [12/59/29] (0/11/8)                           
                                      Tripe                               
D                                     structure                           
                                      tabular grain                       
Emulsion                                                                  
     9.0  0.85 23     5     [8/59/33] (0/11/8)                            
                                      Triple                              
E                                     structure                           
                                      tabular grain                       
Emulsion                                                                  
     14.0 1.25 25     3     [37/63] (34/3)                                
                                      Double                              
F                                     structure                           
                                      tabular grain                       
Emulsion                                                                  
     1.0  0.07 15     1     --        uniform                             
G                                     structure                           
                                      fine grain                          
__________________________________________________________________________
 
    
     In Table 6, 
     (1) The emulsions A to F were subjected to reduction sensitization during grain preparation by using thiourea dioxide and thiosulfonic acid in accordance with the Examples in JP-A-2-191938. 
     (2) The emulsions A to F were subjected to gold sensitization, sulfur sensitization, and selenium sensitization in the presence of the spectral sensitizing dyes described in the individual light-sensitive layers and sodium thiocyanate in accordance with the Examples in EP 443,453A. 
     (3) The preparation of tabular grains was performed by using low-molecular weight gelatin in accordance with the Examples in JP-A-l-158426. 
     (4) Dislocation lines as described in EP 443,453A were observed in tabular grains and regular crystal grains having a grain structure when a high-voltage electron microscope was used. ##STR11## 
     The samples 101 to 104, thus obtained, were exposed and processed by the method specified below: 
     
         ______________________________________                                    
Processing method                                                         
Process        Time       Temperature                                     
______________________________________                                    
Color development                                                         
               3 min. 15 sec.                                             
                          38° C.                                   
Bleaching      1 min. 00 sec.                                             
                          38° C.                                   
Bleach-fixing  3 min. 15 sec.                                             
                          38° C.                                   
Washing (1)    40 sec.    35° C.                                   
Washing (2)    1 min. 00 sec.                                             
                          35° C.                                   
Stabilization  40 sec.    38° C.                                   
Drying         1 min. 15 sec.                                             
                          55° C.                                   
______________________________________                                    
 
    
     The compositions of each processing solutions are given below. 
     
         ______________________________________                                    
                    (g)                                                   
______________________________________                                    
(Color developing solution)                                               
Diethylenetriaminepentaacetic acid                                        
                        1.0                                               
1-hydroxyethylidene-1,1-                                                  
                        3.0                                               
diphosphonic acid                                                         
Sodium sulfite          4.0                                               
Potassium carbonate     30.0                                              
Potassium bromide       1.4                                               
Potassium iodide        1.5    mg                                         
Hydroxylamine sulfate   2.4                                               
4-[N-ethyl-N-β-hydroxylethylamino]-                                  
                        4.5                                               
2-methylaniline sulfate                                                   
Water to make           1.0    l                                          
pH                      10.05                                             
(Bleaching solution)                                                      
Ferric ammonium ethylenediamine-                                          
                        120.0                                             
tetraacetate dihydrate                                                    
Disodium ethylenediaminetetraacetate                                      
                        10.0                                              
Ammonium bromide        100.0                                             
Ammonium nitrate        10.0                                              
Bleaching accelerator   0.005  mole                                       
((CH.sub.3).sub.2 N--CH.sub.2 --CH.sub.2 --S--).sub.2.2HCl                
Ammonia water (27%)     15.0   ml                                         
Water to make           1.0    l                                          
pH                      6.3                                               
(Bleach-fixing solution)                                                  
Ferric ammonium ethylenediamine-                                          
                        50.0                                              
tetraacetate dihydrate                                                    
Disodium ethylenediaminetetraacetate                                      
                        5.0                                               
Sodium sulfite          12.0                                              
Ammonium thiosulfate    240.0  ml                                         
aqueous solution (70%)                                                    
Ammonia water (27%)     6.0    ml                                         
Water to make           1.0    ml                                         
pH                      7.2                                               
______________________________________                                    
 
    
     (Washing solution) 
     Tap water was supplied to a mixed-bed column filled with an H type strongly acidic cation exchange resin (Amberlite IR-120B: available from Rohm &amp; Haas Co.) and an OH type strongly basic anion exchange resin (Amberlite IR-400) to set the concentrations of calcium and magnesium to be 3 mg/l or less. Subsequently, 20 mg/l of sodium isocyanuriate dichloride and 0.15 g/l of sodium sulfate were added. The pH of the solution fell within the range of 6.5 to 7.5. 
     
         ______________________________________                                    
(Stabilizing solution)     (g)                                            
______________________________________                                    
Formalin (37%)             2.0 ml                                         
Polyoxyethylene-p-monononylphenylether                                    
                           0.3                                            
(average polymerization degree = 10)                                      
Disodium ethylenediaminetetraacetate                                      
                           0.05                                           
Water to make              1.0 l                                          
pH                         5.0-8.0                                        
______________________________________                                    
 
    
     The sensitivity is represented by a relative value of the reciprocal of an exposure amount by which a fog density and a density higher by 0.1 than a fog density are given on the characteristic curve of a magenta dye. The gamma was obtained as the slope of a straight line connecting a point of fog+0.1 and a point of fog+0.6. 
     The obtained results are summarized in Table 7 below. 
     
                                           TABLE 7                                 
__________________________________________________________________________
Sample   Chemical                                                         
                Relative                                                  
No. Emulsion                                                              
         sensitization                                                    
                sensitivity                                               
                      Gamma                                               
                           Fog                                            
                              Remarks                                     
__________________________________________________________________________
101 1-B  Gold-sulfur-                                                     
                100   100  0.35                                           
                              Comparative                                 
         selenium             example                                     
102 1-I  Gold-sulfur-                                                     
                120   118  0.15                                           
                              Present                                     
         selenium             invention                                   
103 2-B  Gold-sulfur-                                                     
                102   120  0.35                                           
                              Comparative                                 
         selenium             example                                     
104 2-C  Gold-sulfur-                                                     
                132   123  0.20                                           
                              Present                                     
         selenium             invention                                   
__________________________________________________________________________
 
    
     As can be seen from Table 7, each emulsion of the present invention had a low fog, a high sensitivity, and a large gamma value, demonstrating the significant effect of the present invention.