Let a reliable apothecary put up for you in a small bottle four ounces of ninety per cent alcohol and one ounce of thirty-six per cent nitric acid. One-half of this mixture will disinfect a room fifty feet long, thirty feet wide, and twelve feet high. One large spoonful of it (one-half ounce) will disinfect a large bed-room containing 1,200 cubic feet of air-space. Two tea-spoonfuls of it (two drachms) will disinfect a bed-room nine feet square, and seven and one-half feet high. A tea-spoonful (one drachm) is sufficient for 300 cubic feet of air-space.

The method of using the mixture is as follows: Put the quantity to be used in a porcelain capsule (a tea saucer will do), set a pan of warm water in the room to be disinfected; let the capsule or saucer containing the disinfectant float on the surface of the warm water. The mixture in the floating capsule or saucer will evaporate by the heat of the water, and the vapor will effectively disinfect. Do n't try to evaporate it on a stove, over a lamp, or by a fire; mischief would result. Use exactly warm water to effect evaporation and nothing else. Use only porcelain to hold the mixture, for it will corrode metal. It will also spoil a good spoon. Label the bottle "poison," for it would be very dangerous to take it instead of medicine. The chemist will perceive that the disinfecting vapor evolved is nitrate of ethyl. The alcohol is in excess and so saturates the acid products of the reaction that they are not disagreeable, while they are equally effective.

The material, in the quantity necessary to use, is very cheap, and the method of using it, when clearly understood, is very simple. The vapor evolved, while inoffensive, destroys infected dust and germs of putrefaction floating in the air of a sick-room. It is excellent for hospitals and public buildings; only, in large spaces, the quantity used should be divided and evaporated in different parts of the room. It is sufficient to use it once a day.

Hygienists are indebted to a French scientist, M. Ley-russon, for this ingenious, cheap, and simple method of disinfecting sick-rooms, without danger or even annoyance to the inmates. It has been very recently published in France.