768 A MANUAL OF BACTERIOLOGY 



maintenance of a good room temperature, sealing of the 

 room, the use of at least 60 grm. of formaldehyde per 

 1,000 cubic feet (preferably more, up to 120 grm.), and in 

 the case of large rooms mixture of the gas with the air of 

 the room, either mechanically or by the provision of a 

 multiplicity of inlets for the gas into the atmosphere. By 

 the use of a vacuum formaldehyde can be evaporated in 

 a closed chamber at temperatures indifferent to many 

 substances which will not stand steam at 100, and con- 

 siderable penetration can be obtained (Defries process). 

 As a spray, formalin can be used in any ordinary apparatus. 

 Formalin seems to have a slow germicidal action, for 

 tested by the Rideal-Walker method, the time limit of 

 which is fifteen minutes, its carbolic co-efficient is only 

 about 0-7 for the B. typhosus. Yet 2 per cent, formalin 

 kills anthrax spores in two or three days, and gaseous 

 formaldehyde is similarly active. 



Bacterol is a proprietary formalin-containing disinfec- 

 tant. The vaporising form vaporised in the special 

 Bacterol cabinet is extremely efficient for the destruction 

 of both bacteria and vermin, and it has no deleterious 

 action on any articles. 



Of the aromatic series, the number of substances and 

 preparations is extraordinarily large. The best known is 

 phenol (carbolic acid). Its saturated solution contains 

 about 9 per cent. It is only slightly affected by albumi- 

 noids, and generally is stable in the presence of organic 

 matter at ordinary temperatures. Its compounds, when 

 it forms any, have themselves some disinfectant action. 

 With acids this action is usually greater than that of 

 pure phenol, with alkalies less. Light tends to decompose 

 it, but the efficiency is not affected. It is poisonous and 

 caustic. Its chief use is as a standard, as its disinfec- 

 tant value is comparatively low, and for spore -bear ing 

 organisms it is practically useless. Like the cresols. its 



