Several processes have been published for this beautiful pigment, but probably some minute precautions, not generally known, may be necessary to the production of the finest quality. The climate and state of the atmosphere are said to influence the result.
1. Madame Cenette's process. Into 6 pails of boiling, clear, soft water, in a copper vessel, throw 2 lbs. of powdered cochineal of good "quality; boil for 2 hours, add 3 oz. of purified nitre, and, after a few minutes, 4 oz. of salt of sorrel. Remove the vessel from the fire, let the contents settle for 4 hours, draw off the clear liquor with a syphon into flat plates, and leave it at rest for 3 weeks. Carefully detach the pellicle of mould from the surface, withdraw the liquid with a syphon and pipette, and dry the deposit in a stove.
2. Boil 4 quarts of soft water in a pewter kettle, add to it 4 oz. of finely powdered cochineal; boil for 5 minutes, adding 2 drs. of powdered cream of tartar; then add 8 scruples of Roman alum, and keep the whole on the fire for a minute longer. Let the decoction settle, decant it into cylindrical glasses, and cover them. When the carmine has subsided, pour off the clear liquor, and dry the sediment. By adding solution of tin to the liquid, more carmine is obtained.
3. Into a 14-gallon boiler of tinned copper, put 10 gallons of distilled water, or filtered rain water; when it boils, sprinkle in, by small quantities, 1 lb. of powdered cochineal, and keep it boiling for half an hour. Then add 3 1/2 oz. of crystallized carbonate of soda; in a minute or two, draw the fire, and add 1 1/2 oz. of Roman alum in fine powder; stir with a glass rod till the alum is dissolved, leave it to settle for 25 minutes, draw off the liquor with a glass syphon, and strain the rest through a coarse linen cloth. Clean the boiler, return into it the clear-coloured liquor, and stir into it the whites of 2 eggs, previously well beaten with a quart of warm (not hot) water. Then light the fire, and heat the liquor till it begins to boil; separate the coagulmn by filtration, wash it on the filter with distilled water, spread it thinly on earthen plates, and dry it in a stove,