164 BACTERIOLOGY. 



power of the gas depends not only upon its concentra- 

 tion, but also upon the temperature and the condition 

 of the objects to be sterilized. As with other gaseous 

 disinfectants viz., sulphur dioxide and chlorine it has 

 been found that the action is more rapid and complete 

 at higher temperatures i. e., at 35 to 45 C. (95 to 

 120 F.) and when the test objects are moist than at 

 lower temperatures and when the objects are dry. Still 

 it has been repeatedly demonstrated by actual experi- 

 ment in rooms that it is possible to disinfect the surface 

 of apartments and articles contained in them, under the 

 conditions of temperature and moisture ordinarily 

 existing in rooms, by an exposure of a few hours to 

 a saturated atmosphere of formaldehyde gas. 



Stahl l has shown that bandages and iodoform gauze 

 can be kept well sterilized by placing in the jars con- 

 taining them pieces of <( formolith," a preparation of 

 paraformaldehyde in tablet form containing 50 per 

 cent, of formaldehyde. The same experimenter has 

 also succeeded in making carpets and articles of cloth- 

 ing germ-free by spraying them with 0.5 to 2 per cent, 

 solution of formaldehyde for fifteen to twenty minutes 

 without the color of the fabrics being in any way 

 affected. The investigations of Trillat, Aronson, Pot- 

 tevin, and others have shown that a concentration of 

 f * ne aqueous solution (40 per cent.), equal to 

 ^ P ure formaldehyde, was safe and sufficiently 

 powerful to retard bacterial growth. 



A 2 per cent, watery solution of formalin destroys 

 the vegetative forms of bacteria within five minutes. 

 In our experiments formalin has upon the vegetative 



1 Pharmaceutische Zeitung, No. 22, 1893. 



