CARMINE.

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powder are the chief points which determine its price, and the purer thematerial the better are its qualities.

Pure carmine is entirely soluble in ammonia, and upon that property itsuse in the dyeing of tissues is based. The true nature of the combination ofcarminic acid which forms this compound is unknown ; in its formation theintervention of the nitrogenised matters naturally present in cochineal, or ofthose which can be added to a solution of carminic acid, is required. Thepreparation of carmine itself is not a matter which is very well known ; everymaker keeps secret that method which yields him the most beautiful andremunerative produtft. According to Prof. Girardin, the manufadture wasaccidentally discovered, at Pisa, by a Franciscan monk, who, while experi-menting with cochineal and carbonate of potassa, observed, on adding an acidto that mixture, the precipitation of a beautifully red-coloured substance.Dr. Homberg published, in 1656, a method for the preparation of carmine.Generally speaking carmine is prepared by exhausting previously pulverisedcochineal with boiling water, to which sometimes an alkaline salt is added ;and the precipitation of carmine is effected either by a weak acid or an acidsalt. Sometimes albumen or gelatin is added to the liquid, and also alum.

The following prescriptions are practical, and give an idea of the method ofpreparation of this colouring matter:—Take i kilo, of powdered cochineal,boil with 10 litres of water for a quarter of an hour, add 30 grms. of alum,boil up for three minutes, let settle ; the clear liquid carefully decanted willdeposit, on standing for a few days, from 40 to 50 grms. of carmine ; the cleat-decanted liquid deposits, after some few days longer rest, another but smallerquantity of carmine of inferior shade. Or, take 1 lb. of powdered cochineal,30 lbs. of water, boil for a quarter of an hour, add 30 grms. of best cream oftartar, boil for ten minutes longer, then add 15 grms. of alum, and boil up fora couple of minutes ; the clear and decanted liquid is left to deposit in shallowglass vessels ; the carmine is washed with cold distilled water, and dried care-fully in the shade.

The following is the prescription of Madame Cenette, a lady once in veryextensive business in carmine making) :—Take 2 lbs. of ground cochinealand 150 lbs. of water, boil for two hours; add 3 ozs. of pure nitrate ofpotassa, boil for three minutes longer; add next 4 ozs. of salt of sorrel,boil again for ten minutes ; after the liquid has become clear, by standing fora quarter of an hour, it is set aside in shallow glass vessels for three weeks,after which time the carmine which has deposited is carefully separated fromthe liquid, which, meanwhile, has grown mouldy on the top; the carmine isdried in the shade.

The carmine of commerce is often adulterated with starch, kaolin, Frenchchalk, Vermillion, and sometimes contains small bits of cochineal. Since purecarmine is readily and entirely soluble in ammonia, such adulterations arereadily detected.

Carmine is chiefly used by artists in oil and water colours, for the colouring°f superior bonbons, artificial flowers, and, in rare cases, the printing oftissues. Carmine is chiefly made in Germany, whence it is exported intoother countries. France obtains annually about 400 kilos, of superior, and3500 kilos, of common, carmine from Germany. Carmine of the highestquality, it should be here observed, can only be prepared under certain peculiar