444 DISINFECTION 



with formalin or glyco-formal (30 per cent, formalin with 10 per 

 cent, glycerine), which is thus vaporised and ejected in the form 

 of a fine spray through four nozzles. A room is thereby speedily 

 filled with a dense formalin vapour. After four hours exposure, 

 Houston and the writer found that B. pyocyaneus, Staphylococcus 

 pyogenes aureus, and various saprophytic organisms were kUled.* 

 Klein and the writer found that B. anthracis and the tubercle 

 bacillus were killed by the same means. Eideal claims that the 

 resistant spores of anthrax may be killed when 7'5 c.c. of formalin 

 per cubic metre (85 grammes of formaldehyde per 1000 cubic feet) 

 are vaporised with not less than four times its volume of water, and 

 that exposure need not exceed six hours.f Klein, Houston, and 

 Gordon found that B. typhosus, B. diphtherice, and certain suppu- 

 rative organisms were killed by means of the alformant lamp 

 raethod.J It is agreed that the gas is harmless to colours, metals, 

 leather, and polished wood. The vapour acts best in a warm 

 atmosphere. As for its action on bacteria, it may be said that it 

 compares favourably with any other disinfectant. 



Many observers have not recommended formaldehyde on account 

 of its professed lack of penetrating power. Professor DeMpine, 

 however, states that it possesses "penetration powers probably 

 greater than those of most other active gaseous disinfectants. B. 

 coli, B. tuberculosis, B. pyocyaneus, and Staphylococcus pyogenes aureus 

 were killed in dry or moist state, even when protected by three 

 layers of filter-paper." § In Professor Del^pine's opinion, the 

 vapours of phenol, izal, dry chlorine, and sulphurous acid have, 

 under the same conditions, given inferior results. Since 1898 a 

 number of experimenters have confirmed these opinions. It is 

 extremely important that that disinfectant should be used which is 

 the most suitable one for the particular purpose at issue. A 

 germicidal substance which under certain conditions, and in relation 

 to one species of organism may be practically useless, may under 

 other conditions be most efficacious. 



Ppactical Disinfection II 



To disinfect a room, seal up cracks and crevices, spray the walls 

 with water, and burn, say, 3-6 lbs. of roll sulphur for every 



* Practitioner, 1902, vol. Ixix., p. 328. 



t Jour, of Sanitary Institute, 1903, vol. xxiii., part iv. 



t Report of Medical Officer of London County Council, 1902. 



§ Jour, of State Med., 1898 (November), p. 541. 



II For hints in the detail management of disinfection, the reader is recommended 

 to study A Practical Guide to Disinfection, by Rosenau and Allan, 1903 ; Lessons 

 in Disinfection, by F. W. Andrewes, 1903; the Practitioner, 1902, p. 300 (Houston); 

 Rideal's Disinfection and Disinfectants, 1904 ; and Public Health, 1904, pp. 558-570. 



