402. Disinfectants. It is evident that air and water are not always sufficient to secure disinfection, and this must be accomplished by other means. The destruction of infected material by fire is, of course, a sure but costly means of disinfection. Dry heat, steam, and boiling water are valuable disinfectants and do not injure most fabrics. These agents are generally used in combination with various chemical disinfectants. Certain chemical agents that are capable of destroying micro-organisms and their spores have come, of late years, into general use. A form of mercury, called _corrosive sublimate_, is a most efficacious and powerful germicide, but is exceedingly poisonous and can be bought only under restrictions.[54] _Carbolic acid, chloride of lime, permanganate of potash_, and various other preparations made from zinc, iron, and petroleum, are the chemical disinfectants most commonly and successfully used at the present time. There are also numerous varieties of commercial disinfectants now in popular use, such as Platt’s chlorides, bromo-chloral, sanitas, etc., which have proved efficient germicides. Instructions for the Management of Contagious Diseases. The following instructions for the management of contagious diseases were prepared for the National Board of Health by an able corps of scientists and experienced physicians. 403. Instructions for Disinfection. Disinfection is the destruction of the poisons of infectious and contagious diseases. Deodorizers, or substances which destroy smells, are not necessarily disinfectants, and disinfectants do not necessarily have an odor. Disinfection cannot compensate for want of cleanliness nor of ventilation. 404. Disinfectants to be Employed. 1. Roll sulphur (brimstone); for fumigation. 2. Sulphate of iron (copperas) dissolved in water in the proportion of one and a half pounds to the gallon; for soil, sewers, etc. Note. A most useful little manual to consult in connection with this chapter is the _Hand-Book of Sanitary Information_, written by Roger S. Tracy, Sanitary Inspector of the New York City Health Department. Price, 50 cents.] 3. Sulphate of zinc and common salt, dissolved together in water in the proportion of four ounces sulphate and two ounces salt to the gallon; for clothing, bed-linen, etc. 405. How to Use Disinfectants. 1. _In the sick-room._ The most available agents are fresh air and cleanliness. The clothing, towels, bed-linen, etc., should, on removal from the patient, and before they are taken from the room, be placed in a pail or tub of the zinc solution, boiling-hot, if possible. All discharges should either be received in vessels containing copperas solution, or, when this is impracticable, should be immediately covered with copperas solution. All vessels used about the patient should be cleansed with the same solution.