1 82 Sterilization and Disinfection 



rooms, though Rosenau* finds that unless the spray discharged 

 from a large atomizer be very fine, its action is uncertain. 



The original method of disinfection, suggested by Robinson, f 

 consisted of the evolution of the gas by volatilizing methyl alcohol, 

 and passing the vapor over heated asbestos. Shortly many efficient 

 forms of apparatus were placed upon the market, for the evolution 

 of the gas or for discharging it from the solution. 



It is not necessary to use a special apparatus in order to disinfect 

 with formaldehyd; one can, in an emergency, hang up a number 

 of sheets, saturated with the 40 per cent, solution, in the room to 

 be disinfected. The number of sheets must vary with the size of 

 the room, as each is able to evolve but a certain amount of the 

 gas, and the quantity necessary for disinfection varies with the size 

 of the room. 



One of the best methods of evolving the gas for purposes of dis- 

 infection is that devised by Evans and Russell | who combine the 

 40 per cent, solution of formaldehyd with permanganate of po- 

 tassium, when an almost explosive liberation of the gas takes place. 



Frankforterf found that a good method of escaping the un- 

 desirable features of the gaseous evolution was to mix the powder 

 of permanganate of potassium with an equal volume of sand, so 

 that the formaldehyd solution is brought more slowly into contact 

 with the permanganate, under conditions unfavorable to the forma- 

 tion of oxids of manganese, such as otherwise tend to coat the grains 

 of permanganate and prevent further reaction between the formal- 

 dehyd solution and the permanganate. 



The employment of calcium carbide for the same purpose is 

 suggested by Evans. The best results were obtained when the 

 calcium carbide was in lumps about the size of a pea; when the formal- 

 dehyd solution was diluted with an equal volume of water, and when 

 the diluted formaldehyde was added to the carbide in the propor- 

 tion of 5 cc. of the former to 3 grams of the latter. In the per- 

 manganate method the quantity of formalin (or 37-40 per cent, for- 

 maldehyd in water) should equal 200 cc. to 1000 cubic feet of 

 space, but in the carbide method 500 cc. must be used to achieve 

 the same result. Evans, therefore, prefers the permanganate 

 method. 



To disinfect with formaldehyd or any gaseous disinfectant, the 

 room must be carefully closed, the cracks of the windows and 

 doors being sealed by pasting strips of paper over them. If an 

 apparatus is used, it is set in action, the discharged vapor entering 

 the room through the keyhole or some other convenient aperture, 



*" Disinfection and Disinfectants," P. Blakiston's Son & Co., Philadelphia, 

 1902. 



f "Ninth Report of the State Board of Health of Maine," 1896. 



I" Reports and Papers of the American Public Health Association," 1906, 

 vol. xxxn, part n, p. 114. 



Ibid., p. 108. 



