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 httle 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 pex-ceru Lformalde hyd^. 

 called formalin. Formalin is the preparation com- 

 monly used for disinfecting purposes. 



Formaldehyde is considered the most valua ble 



-l ^nriMTi dis infectant for room disinfection following 



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



not tarnish metals nor discolor fabric s, 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 



