=Heat.=—Boiling is a good disinfectant. Boil for at least an hour. If dry air is used, the temperature must be from 250° to 300° for five or six hours. Cotton and silk will stand a temperature of 295° for three hours without harm. Woolen suffers more. =Iron, Sulphate of.= See =Copperas=. =Lime.=—Twenty parts of quicklime, mixed with two parts of dry, fresh charcoal, form the =calx-powder=, as sold in the shops. It is useful to absorb putrid gases, when sprinkled in cellars, etc. =Sulphate of lime=, or =gypsum= (plaster of Paris), mingled with coal-tar or impure carbolic acid, is an effective deodorant for stables and manure-heaps. It absorbs and retains ammonia, and therefore preserves to the manure its most valuable constituent. =Chloride of lime.= See =Chlorine=. Quicklime, 5 cents a pound. Gypsum, 10 cents a pound. =Nitrate of Lead.=—Theoretically a good disinfectant, but practically of little use. Five cents an ounce. =Nitrous Acid.=—Evolved in the form of brownish-red fumes, when nitric acid is poured on copper turnings. Very dangerous to inhale, and little used as a disinfectant. =Ozone.=—Is a form of oxygen, supposed to be three volumes condensed into two. Is a powerful oxidizer. Corrodes cork, paper, and other organic substances. Oxidizes very rapidly compounds of ammonia, phosphorus, and sulphur, which are offensive, instantly removing the odor. Simple vegetables, like mould, are completely destroyed by it. Obtained by gradually mixing three parts of sulphuric acid with two parts of permanganate of potash. This mixture will continue to give off ozone for several months. Or, put a piece of phosphorus on a plate, and pour in water sufficient to cover two thirds of it. These methods are used in the patented ozone generators. Phosphorus, 40 cents an ounce; sulphuric acid, 5 cents an ounce. =Permanganate of Potash.=—Dark purple crystals, almost black. A solution is of a beautiful purple color, but stains brown almost everything it touches. Can not be used with carbolic acid or the coal-tar disinfectants. Is a powerful oxidizer, and is used to disinfect excreta, and to purify drinking-water. Fifty cents an ounce. =Sulphate of Iron.= See =Copperas=. =Sulphate of Lime.= See =Lime=. =Sulphate of Zinc.= See =Zinc=. =Sulphurous Acid.= An irrespirable gas, produced by burning sulphur. Powerful disinfectant. Coagulates albuminous matters and probably destroys germs. Destroys sulphureted hydrogen and ammonia. Dry articles are not hurt by it, but wet clothes are bleached. Can not be used with chlorine, as they neutralize each other. Chlorine is as effective, but is so destructive that it can only be used in empty rooms. It requires about a tablespoonful of alcohol to light a pound of sulphur. Sulphur (roll-brimstone), 10 cents a pound. =Thymol.= See =Carbolic Acid=.