surfactants which can be employed in the practice of the present invention include c 8 to c 18 primary fatty amines or mixtures thereof , corresponding to the formula rnh 2 wherein the r group comprises a c 8 to c 18 alkyl group . specific surfactants which can be employed include , for example , cocoamine , dodecylamine , tetradecylamine , decylamine , octylamine , etc . the reaction time of any aqueous acidizing acid solution for calcareous formations , e . g . limestone , dolomite and other formations , can be increased by incorporating into the acid a sufficient quantity of the above - identified surfactant . there appears to be no critical quantity and the amount employed will depend on such factors as desired increase in reaction time , economic considerations and the like . suitable results can be obtained when as little as about 0 . 1 per cent by weight of the surfactant is employed . economic considerations generally dictate a maximum amount of about 10 per cent by weight of surfactant in the acidizing formulations . acidizing acids which can be employed include hcl , hf , formic acid , acetic acid , sulfamic acid , various mixtures thereof and other acids which are compatible with the specific surfactants employed . the acid solutions can contain up to about 30 per cent by weight or more of the acid . the surfactants of the present invention are especially useful in solutions containing more than about 15 per cent by weight of an acidizing acid , e . g . hcl . the surfactants which are useful in the practice of the invention , e . g . amines , are difficult to disperse into aqueous acidizing formulations . thus , it is often desirous , especially when batch mixing procedures are employed to employ , with the surfactant , a dispersing agent ( e . g . a surface active agent ) such as a quaternary amine , e . g . lauryl dimethyl benzyl ammonium chloride or octyl dimethyl ammonium chloride and the like to aid in dispersing the surfactant into the aqueous solution . if the cationic surfactant is added to a moving stream of the acid formulation , the dispersing agent may be dispensed with . it has been found , in contrast to the teachings of u . s . pat . no . 3 , 319 , 714 , col . 4 , lines 54 - 60 , that certain cationic surfactants have as good a retarding effect in acidic formulations , and in some circumstances a better retarding effect than do certain anionic surfactants . the reason for this result is not known . however , the present invention now makes it possible to employ cationic surfactants in these acid solutions . the method and composition of the present invention is practiced using standard acidizing equipment and procedures well known in the art . the composition and method can be employed in matrix and fracturing acidizing techniques . further , the composition may contain other constituents , e . g . freezing point depressants , corrosion inhibitors , etc ., well known in the art . a series of tests were performed to determine the ability of a particular surfactant to form a tenacious oil film on a limestone surface , i . e . render the surface oil - wet . over 400 surfactants were tested . two per cent by volume of a specific surfactant was mixed into kerosene . a 1 inch by 1 inch by one - quarter inch limestone coupon was then soaked in the kerosene surfactant solution for 1 minute . the coupon was then removed from the kerosene surfactant solution and placed in a 15 per cent hydrochloric acid solution . the surface of the coupon was observed to determine the length of time before the coupon started to react with the hcl solution . those kerosene surfactant solutions which produced a 5 second or longer delay in the time required for acid reaction over the entire surface were tested further as follows . the second stage testing of various surfactants as retarders involved the determination of actual reaction rates in 15 per cent hcl under 1 , 000 psi pressure . tests were performed under static conditions using a high pressure reaction rate cell maintained at room temperature . reaction rates were run on 1 inch × 1 inch × 1 / 4 inch bedford limestone coupons which had previously been weighed . the acid solution to be tested was composed of 90 ml of 15 per cent hcl , 0 . 4 ml of a known corrosion inhibitor , 10 ml kerosene and 2 ml of a specific surfactant . the coupon and acid solution were placed in the cell and the cell pressured , with nitrogen , to 1000 psi . the test was begun by inverting the cell , thus exposing the coupon to the acid . at the end of the test period ( 5 minutes ), the cell was again inverted , the pressure released , and the coupon removed , dried and weighed . reaction rates were then calculated . results using some of the surfactants tested are set forth in the following table i . table i______________________________________ reaction rate ( lb / ft . sup . 2 / sec ) surfactant (× 10 . sup .. sup .- 4 ) ______________________________________none 2 . 54c . sub . 14 alkyl sulfonate . 16dodecyl benzene sulfonic acid . 17amine salt of alkyl benzene . 19 sulfonic acidcocoamine . 27amine alkyl aryl sulfonate . 08alkyl sulfonate . 16anionic sulfate salt . 11calcium sulfonate . 14lauryl sulfate 1 . 14dimethyl cocoamine salt of ortho - . 28 phosphoric acid neutralized with sodium hydroxide______________________________________ those surfactants which showed some ability to retard 15 % hcl ( i . e . showed a reaction rate of less than about 0 . 002 lbs . per sq . ft . per sec .) were next tested employing a 28 % hcl solution . test conditions were the same as employed in the second stage test described above , except that 28 % hcl was used . three surfactants , primary cocoamine , lauryl sulfate and dimethyl cocoamine salt of orthophosphoric acid neutralized with sodium hydroxide showed reaction rates of 0 . 18 ; 0 . 26 and 0 . 66 lbs / ft 2 / sec × 10 . sup . - 4 , respectively . the next best surfactant was dodecyl benzene sulfonic acid 1 . 12 lbs / ft 2 / sec × 10 . sup . - 4 and a linear alkyl aryl sulfonic acid 1 . 76 lbs / ft 2 / sec × 10 . sup . - 4 . these latter two rates are too high to be considered of practical importance . the three surfactants listed above which demonstrated rates of 0 . 66 lbs / ft 2 / sec × 10 . sup . - 4 or less were next tested under conditions of reduced surfactant and kerosene concentration . test conditions were the same as in previous tests except as noted in the following table ii . the reduction in surfactant and kerosene concentration greatly reduced the degree of retardation of the acid solution , i . e ., the reaction rate was increased . of the three surfactants tested , primary cocoamine showed the greatest retarding effect at the lower concentrations employed in this test . the results of these tests are set forth in the following table ii . table ii______________________________________ reaction rate ( lb / ft . sup . 2 / sec ) surfactant kerosene (× 10 . sup .. sup .- 4 ) ______________________________________none 3 % 2 . 741 % primary cocoamine 3 % . 571 % primary cocoamine none 2 . 881 % lauryl sulfate 3 % 2 . 062 % lauryl sulfate none 2 . 491 % dimethyl cocoamine 3 % 1 . 29 salt of orthophosphoric acid neutralized with sodium hydroxide2 % dmethyl cocoamine none 2 . 14 salt of orthophosphoric acid neutralized with sodium hydroxide______________________________________ a series of retarding tests were performed employing cocoamine in the pressurized cell described in example 1 . in this series of tests the coupon was saturated with kerosene prior to the test . no kerosene was added to the acid solution . the amount of primary cocoamine employed in 28 % hcl was varied to determine the effect on the reaction rate of the acid . the results of these tests are set forth in the following table iii . table iii______________________________________ reaction ratepercent of cocoamine ( lb / ft . sup . 2 / sec ) in 28 % hcl (× 10 . sup .. sup .- 4 ) ______________________________________1 . 490 . 5 . 550 . 25 . 940 . 10 1 . 19______________________________________ various other amines were tested as retarders in 15 and 28 % hcl by the test procedure described in example 2 . the results of these tests are set forth in the following table iv . table iv______________________________________ reaction rate percent by hcl conc . ( lb / ft . sup . 2 / sec ) amine wt . in hcl percent (× 10 . sup .. sup .- 4 ) ______________________________________none 15 1 . 59none 28 1 . 62hexyl amine 0 . 5 15 1 . 87hexyl amine 0 . 5 28 1 . 86octyl amine 0 . 5 15 1 . 54octyl amine 0 . 5 28 . 88tetradecylamine 0 . 5 15 1 . 12tetradecylamine 0 . 5 28 1 . 95hexadecylamine 0 . 5 15 1 . 98hexadecylamine 0 . 5 28 1 . 76octadecylamine 0 . 5 28 1 . 67cocoamine 0 . 5 15 . 22cocoamine 0 . 5 28 . 40oleyl amine 0 . 5 28 1 . 67cotton seedamine 0 . 5 28 1 . 60tallow amine 0 . 5 28 2 . 72dicocoamine 0 . 5 28 1 . 61dimethylcocoamine 0 . 5 28 5 . 11______________________________________ a formulation was prepared which represents the manner in which a surfactant retarder composition may be premixed and then incorporated into an acidizing acid . 45 . 5 cocoamine9 . 0 lauryl dimethyl benzyl ammonium chloride ( dispersant ) 16 . 0 methyl alcohol17 . 0 h . sub . 2 o12 . 5 acetic acid reaction rate tests were performed in a dynamic pressurized cell employing 28 per cent hcl and 20 per cent hcl containing 1 . 1 per cent by volume of the above defined formulation . the reaction rate determined for the 28 per cent hcl solution was 10 ( lb / ft 2 / sec ) × 10 . sup . - 4 and with 1 . 1 per cent by volume of the above formulation the reaction rate was 2 . 0 ( lb / ft 2 / sec ) × 10 . sup . - 4 . the 20 per cent hcl solution had a reaction rate of 11 . 0 ( lb / ft 2 / sec ) × 10 . sup . - 4 and the reaction rate of the 20 per cent hcl containing 1 . 1 per cent by volume of the above formulation was 0 . 6 ( lb / ft 2 / sec ) × 10 . sup . - 4 .