Different samples examined (Waller), containing from .20 to .78 per cent, cost from 50 cents to $1 a pint. Crude acid, containing 50 per cent of acid, with many tarry impurities, costs less than $1 a gallon. Thymol, $1 per ounce. =Charcoal.=—Absorbs putrid gases. See =Lime=. =Chloride of Lime.= See =Chlorine=. =Chloride of Zinc.= See =Zinc=. =Chlorine.=—A pale, yellowish-green gas, of a suffocating quality, possessing great bleaching and disinfecting powers. When dry, it does not bleach. When moist, it combines with the hydrogen of water or of organic substances, and sets free the oxygen, which constitutes its disinfecting power. It decomposes sulphureted hydrogen, ammonia, and in general compounds arising from the putrid fermentation of organic matter. It is obtained as follows: Pour one pound of sulphuric acid, previously diluted with four times its volume of water, on three pounds of chloride of lime. Mix in a large earthen dish to allow for frothing up. Or mix two parts, by weight, of the black oxide (dioxide) of manganese with three parts, by weight, of strong hydrochloric acid. The gas is evolved very rapidly, so that it is difficult to make the mixture complete before the fumes drive away the person manipulating it. The colors of hangings, etc., are apt to be bleached out by it, and metals are corroded. (See also =Sulphurous Acid=.) =Chloride of Lime.=—Made by saturating slaked lime with chlorine-gas. It contains on an average about 30 per cent of available chlorine, to be set free by an acid. Very useful for disinfection of cellars, damp yards, and areas. One half pound in a gallon of water may be used for washing floors of sick-rooms, etc. Heat destroys its disinfecting properties. =Chloride of Aluminum.=—Action similar to but weaker than the iron and zinc salts, Sulphuric acid, black oxide of manganese, and hydrochloric acid, each 5 cents an ounce. Chloride of lime, 15 cents a pound. =Copperas.= (Green vitriol, sulphate of iron.)—Comes in pale-green crystals. It is an efficient disinfectant for privies, water-closets, stables, etc. Stains white goods. Acts by destroying sulphureted hydrogen and ammonia. Also oxidizes organic compounds and coagulates albuminous matters. A good mixture is four pounds of copperas and three ounces of carbolic acid to a gallon of water. Ten cents a pound. One hundred pounds for $3 or less. =Corrosive Sublimate.= (Mercuric chloride.)—The most powerful disinfectant known. Coagulates albuminous substances. A solution of one part in 2,000 of water kills microscopic organisms. Two drachms of this substance in a gallon of water (1 to 500) makes a solution sure to destroy any disease-germ. It is a deadly poison, and can only be purchased under legal restrictions. Fifteen cents an ounce. =Dead Oil.= See =Carbolic Acid=. =Green Vitriol.= See =Copperas=. =Gypsum.= See =Lime=.