PHYSICAL AND CHEMICAL AGENTS 39 



very dirty wooden floors will not only remove but 

 disinfect the filth. 



The commercial medicated soaps are said to be 

 of little value. Abbott gives a formula for carbol- 

 soap which has the same disinfectant value as pure 

 carbolic acid, is easily made, and particularly valu- 

 able for the disinfection of washable clothing : 

 Dissolve 3 parts green soap in 



100 parts of warm water, add 

 5 parts commercial carbolic acid, stirring 

 slowly. 



Formaldehyde is a gas which, dissolved in water, 

 gives a solution of about 40 per cent formaldehyde, 

 called formalin. Formalin is the preparation com- 

 monly used for disinfecting purposes. 



Formaldehyde is considered the most valuable 

 known disinfectant for room disinfection following 

 all infectious diseases ; it is also a deodorizer ; it does 

 not tarnish metals nor discolor fabrics, and the gas 

 is not poisonous, although extremely irritating. 



In fumigating with formalin all cracks and crevices 

 must be tightly packed. There are several especially 

 designed lamps and generators in use, the principle 

 of all being to liberate the gas by heat, but except 

 for hospitals or other large institutions they are too 

 expensive for general use and the simple method of 



