referring to fig1 to 5 , the fragrance cartridge 10 according to a first embodiment of the present invention comprises a ceramic outer shell 12 and a gel composition 14 contained within and retained by the outer shell 12 . the embodiment is intended to provide a solid cartridge for use with dispensers such as that illustrated in fig6 . this is intended to alleviate problems relating to leakage and spillage , and avoid the need to “ prime ” the system ( i . e . draw fluid from the cartridge into a dispensing mechanism ). the cartridge thus comprises a large moulded ceramic block impregnated with a fragrance complete with an integrated fragrance gel core working uniquely together in a timed release phase to provide consistent fragrance performance whilst overcoming fragrance fatigue issues . the product contains no liquid , so there is no chance of leaking in transit or use . it is classed as non - hazardous for all shipping methods . the external shape of the cartridge is intended to be a universal fit , i . e . one that fits into all existing dispensers . the fragrance impregnated into the ceramic block is different to that provided in the gel core . this allows us to produce a multi fragrance product , with effects and characteristics that change substantially over time . these fragrances are designed such that the focus of the fragrance ( the powerful key chemicals and notes ) are significantly different . the diffusion rate of fragrance moving through ceramic is non - trivially different to that of fragrance evaporating from the surface of the gel . this allows us to design different mixtures to evaporate at different rates , so that one can be longer lasting than the other . these different mixtures ( fragrances ) can be chosen to be complementary , so that one fragrance (“ a ”) in the gel and one fragrance (“ b ”) in the ceramic , combine to produce a multitude of fragrances starting from primarily ( a ) or ( b ), developing over time to something in the middle being a balance of ( a ) & amp ; ( b ) and ending with either ( b ) and ( a ) [ respectively ]. further , the fragrances for each part can be made of faster and slower evaporative chemicals ( or groups of fragrance notes ), such that each part ( a ) or ( b ) can have many sub - fragrances ( a 1 , a 2 , a 3 , and b 1 , b 2 , b 3 ) that interact with each other to form other final fragrances in the air . this type of product would be difficult to become accustomed to , and fragrance fatigue would be avoided . the fragrance gel compounds that we prefer are generally composed of : gels contain a carrier material , from which the perfume evaporates slowly and thus gives a pleasant smell to the atmosphere . the life time and the amount of perfume emitted per time unit are determined mainly by the amount of perfume in the air - freshener . in many known types of air - fresheners gelled water is used as carrier material . however , as perfumes are generally not or only hardly soluble in water , they should be dispersed therein as homogeneously as possible . gelled organic solvents such as monohydric or polyhydric alcohols or glycol ethers can also be used as a carrier material , but water has the advantage of being cheap and toxicologically unsuspected . aqueous gels can be prepared in a wide range of known ways , using as a gelling agent compounds such as vegetable gums , especially carrageenan , agar - agar , alginates , pectin , guar gum , tragacanth , karaya gum and xanthan , or compounds such as gelatin , starch and cellulose derivatives . in some cases the gel strength can be increased by the addition of salts of bivalent or polyvalent metals like ca , mg , al or cr . alternatively , synthetic polymers such as polyvinyl alcohol may be used as gelling agent . such aqueous gels have the disadvantage that they may only contain a limited amount of perfume . in the literature a maximum perfume content of typically about 10 % is mentioned , but in practice it appears that from a perfume content of more than about 6 % strongly reduces the gel strength and / or causes syneresis whereby the perfume leaves the gel as a liquid . aqueous perfume gels are described for instance in published japanese patent applications 54 / 110 , 990 ( gelling agent : carragheenin and sodium stearate , perfume content up to 6 %); 53 / 088 , 334 ( gelling agent : bacterial polysaccharide , 1 - 10 % of perfume ); and 52 / 136 , 893 ( gelling agent : carragheenin and polyvinyl alcohol , 2 - 4 % of perfume ), and in french patent application 2 , 293 , 976 ( gelling agent : carboxymethyl cellulose / ai - salt , 5 % of perfume ). dutch patent application 76 , 11041 also discloses the use of carboxymethyl cellulose and salts of trivalent metals as gelling agent in aqueous perfume gels . although it is mentioned in the specification that these gels may contain up to 20 % of perfume , the examples only illustrate a perfume content of 4 %. likewise , dutch patent application 76 , 02254 discloses similar aqueous perfume gels which are said to be capable of containing up to 10 % of perfume , whereas in the examples only gels containing up to 23 % of perfume are described . dutch patent application 75 , 02596 describes aqueous gels based on mixtures of carragheenin and locust bean gum which according to the specification may also contain up to 10 % of perfume , but from the examples it appears that no more than 3 . 3 % of perfume is used . dutch patent application 76 , 12909 discloses gels based on amylose as gelling agent ; in the specification it is indicated that the perfume content of these gels is 0 . 25 - 30 % preferably 0 . 5 - 5 %. an example discloses a gel containing 30 % of perfume , but for that result a content of 10 % of pure amylose is required , with an attendant cost penalty . when starch containing 70 % of amylose is used , no stable gel can be produced with even 10 % of perfume . furthermore these gels have the disadvantage that for the preparation of the necessary amylose - solution high temperatures ( up to 170 ° c .) and pressures ( up to 7 atm ) are required , which therefore involves some relatively complicated equipment . in some of the above - mentioned patent applications , it is mentioned that the perfume is preferably used together with an amount of emulsifier for promoting the homogeneous distribution of the perfume in the aqueous phase . in japanese patent application 52 / 070 , 035 it is stated that aqueous gels cannot contain more than 2 - 3 % of perfume , except when a non - ionogenic emulsifier is added in an amount of 0 . 5 - 1 . 5 times the amount of perfume , in which case the perfume content of the gel may rise to 10 %. the amount of perfume which can be distributed homogeneously in an aqueous gel highly depends on the solubility of the perfume in water and thus on the type of the composing components of the perfume . the phrase “ perfume ” is used to mean a mixture of organic compounds such as aldehydes , ketones , nitriles , esters , carboxylic acids , alcohols and ethers which may also contain natural products like essential oils , resinoids , balsams and concretes . this mixture is meant to emit the desired smell . in many cases a perfume contains a mostly small amount of a solvent or diluent usual in perfumery , for instance because one or more of the components used in the composition are only available or manageable in solution . part of the water used for preparing the gel can optionally be replaced by water - miscible organic solvents like monohydric or polyhydric alcohols , for instance ethanol , isopropanol or ethylene glycol , as far as these solvents do not affect the good activity of the gelling agent used . this replacement is not generally recommended , but purely for economic reasons as organic solvents are more expensive than water . the ceramic part can be constructed of any suitable adsorbent ceramic . we prefer on including 5 to 20 % of portland cement clinker together with the remaining 80 to 95 % being made up of a plaster composition , ideally calcium sulphate hemihydrate , aka plaster of paris or gypsum plaster . these compound mixtures form a durable and stable greenware ( i . e . an unfired ceramic ) that is highly absorbent . it could optionally be fired in order to provide a harder surface without the loss of absorbency . the portland cement clinker is a mix of calcium silicates produced in the manufacture of portland cement by sintering limestone and alumino - silicate ( clay ). for our purposes , it should consist of at least two - thirds by mass of calcium silicates ( tricalcium silicate 3cao • sio 2 and dicalcium silicate 2cao • sio 2 ), the remainder consisting substantially of aluminium - and iron - containing clinker phases and other compounds . the ratio of cao to sio 2 should ideally not be less than 2 . 0 . any magnesium oxide content ( mgo ) should ideally not exceed 5 . 0 % by mass . this compound can then be modified with pozzolan type materials , if desired . further details of the cement composition can be found at http :// en . wikipedia . org / wiki / clinker ( cement ). this compound can absorb essential oil , aromatics , hydrocarbons , deodorizing compounds and fragrance oils in amounts up to 150 % of the ceramic &# 39 ; s weight . the porosity is generally low hydrophobic or lipophilic conductivity . the porosity & amp ; retentive qualities of the above “ ceramic ” type materials and blends allow the product to “ hold ” these fragrance compounds for extended periods of time , giving a time release quality and not allowing these compounds to leak and do damage . these slow release characteristics are particularly advantageous to the products longevity & amp ; functionality . the actual physical construction of the “ ceramic ” cartridge is produced by hydrating the above blend of plaster & amp ; cement clinker with water and casting it . the cast part is then allowed to “ dry ” or hydrate until the moisture content allows compounds of essential oils , aromatics , hydrocarbons , deodorizing compounds and fragrance oils to be absorbed without causing separation . as can be seen in fig4 , the ceramic outer shell 12 is in a generally cylindrical form , with an internal closed bore 16 for receiving the gel composition 14 . thus , a base or lower portion 18 of the cylinder is closed , whereas an upper or top portion 20 of the cylinder is open . this means that the gel composition 14 is adequately supported , but also exposed to the atmosphere via the upper portion 20 thereby allowing it to evaporate . the bore 16 tapers so that near to the closed end 18 it is narrower in width than near to the open end 20 ; this aids insertion of the gel composition 14 . a recess 22 is provided on the external part of the base portion 18 , for receiving a locating peg provided in certain dispensers ( fig6 ). this then holds the cartridge 10 in a secure manner . as can be seen most clearly in fig5 , the external sides of the ceramic shell 12 are formed with an indentation 24 , defining a part - annular recess around the shell 12 . this accepts a resilient plastics part - annular or c - shaped clip 26 that fits into the recess and holds the ceramic shell 12 . at the ends of the part - annular clip 26 , there are inwardly directed hooks 28 that engage with corresponding recesses 30 in the indentation 24 , to allow the clip 26 to engage positively with the shell 12 . the clip 26 also has a backplate 32 with engagement formations 34 to allow the clip to be attached to a dispenser housing , thereby supporting the cartridge 10 in place . the clip 26 may be one selected from a variety of clips , each having a backplate suited to one or more different types of dispenser , thus allowing the cartridge to fit any chosen design of dispenser . fig6 shows a typical dispenser housing . a detailed description is given in ep - a - 2113259 , to which the reader is referred for a fuller understanding and which is hereby incorporated by reference . this comprises a baseplate 50 and a cover 52 which is attached to the baseplate 50 via a hinge at their upper edges . thus , the cover 52 may be lifted up on the hinge to reveal the interior of the housing . formations on the baseplate 50 allow the baseplate 50 to be attached to a wall ( or the like ) via screws , bolts , or the like . a cartridge 10 can then be clipped to the baseplate 50 and the cover 52 closed to conceal the cartridge . apertures on the sides ( 54 ), base ( 56 ) and front ( 58 ) faces of the cover 52 allow the fragrance emitted by the cartridge to escape into the room in which it is fitted . a lock mechanism prevents unauthorised opening of the cover 52 , and is released by insertion of a special tool into apertures 60 . fig7 and 8 show a second embodiment of the present invention . the cartridge 100 once again comprises a ceramic outer shell 112 and a gel composition 114 within a recess 116 formed within the ceramic shell 112 . in these and most respects this embodiment corresponds to the above - described embodiment of fig1 to 5 . however , in addition , this embodiment comprises a liner 170 which sits between the gel composition 114 and the internal faces of the recess 116 . the liner is of an impermeable material ; various plastics materials such as polypropylene , polyethylene , polyvinylchloride , and the like , or materials such as latex , rubber , silicone and the like . this prevents mixing of the fragrances in the gel and in the ceramic , and assists in keeping the two fragrances distinct . fig9 shows the fragrance cartridge 10 / 100 as supplied ready for fitting within a dispenser housing . this cartridge may be according to the first or the second embodiment as desired . it sits within a receptacle 80 which has a cap 82 engaging via a screw - thread 84 . the receptacle 80 is sized to fit around the cartridge 10 / 100 and has a bulge 86 on its base designed to engage with the recess 22 on the underside of the cartridge 10 / 100 . this holds the lower part of the cartridge 10 / 100 in place , whilst the upper end is held in place by an inner lid 88 that fits on the top of the cartridge prior to fitting the cap 82 . the inner lid 88 is generally conformal to the upper face of the cartridge 10 / 100 and has a resilient annular u - section ring 90 around the outside of the cartridge 10 / 100 . this sits between the outer cylindrical face of the cartridge 10 / 100 and the inner cylindrical face of the receptacle 80 , and thus braces the cartridge against movement , holding it in position . the inner lid 88 ends with a short lip that is sandwiched between the receptacle 80 and the cap 82 , thus securing the inner lid 88 in place . thus packaged , the cartridge can be transported at will without risk to the ceramic shell . minor bumps or knocks will be absorbed by the receptacle or the lid without causing damage to the cartridge . as the packaging is closed , evaporation of the fragrances will be inhibited . other arrangements for packaging of the fragrance cartridge are possible , of course . for example , it could be enclosed within a frangible membrane such as a shrink - wrap plastics sleeve . it will of course be understood that many variations may be made to the above - described embodiment without departing from the scope of the present invention .
a fragrance dispenser comprises a ceramic outer shell containing a gel composition . the ceramic can be greenware , and can be impregnated with a fragrance , such as in the form of a volatile oil . the gel composition can contain fragrance or deodourisers that can diffuse out of the gel and infuse the surrounding ceramic , from which it can be released into the air . the ceramic cartridge can have indentations to allow it to be retained in a desired location ; these can permit the attachment of a plastic mounting clip having a plurality of flexible arms that slot into the indentations to grip and hold the cartridge in place . this mounting clip could then be used to attach the cartridge to suitable surfaces such as a bathroom wall or the interior of a dispenser housing . furthermore , the cartridge can have a locating recess on one or more of its sides , to receive a mounting post and thereby position the dispenser accurately and inhibit dislodgement .