THE DESTRUCTION OF BACTERIA 89 



purpose about three pounds of sulphur should be burned for every 

 thousand cubic feet of space. It should be allowed to act for not less 

 than twenty-four hours. The researches both of Wolffhiigel ^ and of 

 Koch 2 have shown that the gas is not sufficient for the destruction of 

 spores, under the best circumstances, probably because of its lack of pen- 

 etrating power. Park ' beheves that sulphur dioxide used in quantities 

 of four pounds of sulphur to 1,000 cubic feet is of practical value for 

 fiunigating purposes in cases of diphtheria and the exanthemata. 



Of all known gaseous disinfectants by far the most reliable is form- 

 aldehyde. There are many methods of generating this gas, and many 

 devices for its practical use have been introduced. In all cases where 

 formaldehyde fumigation is intended, clothing, bed-linen, and fabrics 

 should be spread out, cupboards and drawers freely opened. The 

 cracks of windows and doors should be hermetically sealed with paper 

 strips or by calking with cotton. The generation of gas may be carried 

 out in an apparatus left within the room or it may be generated outside 

 and the gas introduced by a tube passed within the keyhole. In all 

 cases moisture should be provided for, either in the generating appa- 

 ratus or by a separate boiler. 



The first of the methods of generating formaldehyde for fumigation 

 purposes was that of Trillat,* who devised a lamp in which formaldehyde 

 was produced by the incomplete combustion of methyl alcohol. This 

 method has proved expensive because of the complete oxidation of a 

 large percentage of the alcohol. 



Direct evaporation of formaldehyde from formalin solutions has been 

 the principle underlying some other devices. If such evaporation is 

 attempted from an open vessel, however, polymerization of formal- 

 dehyde to the solid trioxymethylene occurs. To prevent this, Trillat * 

 and others have constructed special autoclaves in which 20 per cent of 

 calcium chloride is added to formalin which is then vaporized under 

 pressure. By this means polymerization is practically eliminated. 



The Trillat autoclave, as well as others constructed on the same 

 principle, consists of a strong copper chamber of a capacity of about a 

 gallon, fitted with a coyer which can be tightly screwed into place. 

 The cover is perforated by an outlet vent, a pressure gauge, and a 



' Wolffhiigel, Mitt. a. d. kais. Gesundheitsamt, i, 1881. 



' Koch, Mitt. a. d. kais. Gesundheitsamt, i, 1881. 



'Park, "Pathogen. Bact.," N. Y., 1908. 



* Trillat, Compt. rend, de I'acad. des sc, 1892. 



' Trillat, Compt. rend, de I'acad. des sc, 1896. 



