THE PRACTICE OF DISINFECTION 163 



There are various methods of generating formaldehyd 

 gas, and a number of lamps have been constructed for 

 the purpose. Of late good results have been reported by 

 mixing the solid commercial formalin or paraform with 

 potassium permanganate, using 6 ounces of each for 

 1000 cubic feet of air space. 



A special apparatus has been constructed for this, but 

 it is possible to carry it out by using a deep enameled 

 pail. The formalin or paraform must be thoroughly 

 broken up before the permanganate and water are 

 added, otherwise much will remain unaltered and will 

 not be converted into gas. The fumes are kept in the 

 room for twelve hours, and when the process of disinfec- 

 tion is completed they may be displaced by ammonia. 

 Formaldehyd does not injure wool or silk, gilt, copper, 

 or leather. 



Formaldehyd is a very efficient surface disinfectant, 

 but under ordinary circumstances it does not pene- 

 trate to any depths. The "Japanese method" secures 

 much greater penetration. In this the formaldehyd gas 

 is diffused, by means of a rather complex apparatus, 

 throughout steel chambers which have previously 

 been heated to 65 C. Clothing, rugs, etc., are exposed 

 to these formaldehyd vapors for fifteen minutes with 

 satisfactory results i. e., bacteria in the interior of the 

 bundles were destroyed. 



So far as the need of fumigation is concerned, the reader 

 is referred to page 56. 



The use of chlorin in the disinfection of water supplies 

 has already been described. (See pages 39 and 145.) 



Fumigation is still highly important to kill vermin. An 

 ingenious apparatus for thus disinfecting railway coaches 



