114 PRINCIPLES OF BACTERIOLOGY 



quantity without serious results; and trioxymethylene has been givenrj 

 in doses up to 90 grains as an intestinal antiseptic. The vapors OM 

 formaldehyde are extremely irritating to the mucous membrane of theJ 

 eyes, nose, and mouth, causing profuse lacrymation, coryza, and flow* 

 of saliva. Aronson reports that in many of his experiments rabbits* 

 and guinea-pigs allowed to remain for twelve and twenty-four hourss 

 in rooms which were being disinfected with formaldehyde gas were* 

 found to be perfectly well when the rooms were opened. On autopsyv 

 the animals showed no injurious effects of the gas. Others have noticedl 

 that animals, such as dogs and cats, which have accidentally been con- 

 fined for any length of time in rooms undergoing formaldehyde disin- 

 fection occasionally died from the effects of the gas. Many observers,, 

 however, have reported that insects, such as roaches, flies, and bed-- 

 bugs, are not, as a rule, affected. The result of these observations < 

 would seem to indicate that although formaldehyde is comparatively, 

 non-toxic to the higher forms of animal life, nevertheless a certain i 

 degree of caution should be observed in the use of this agent. 



The results of numerous experiments have shown that in the airi 

 2.5 per cent, by volume of the aqueous solution, or 1 per cent, by volume 

 of the gas, are sufficient to destroy fresh virulent cultures of the common i 

 pathogenic bacteria in a few minutes. The researches of Pottevin i 

 and Trillat have shown that the germicidal power of the gas depends '> 

 not only upon its concentration, but also upon the temperature and the 

 condition of the objects to be sterilized. As with other gaseous disin-' 

 fectants viz., sulphur dioxide and chlorine it has been found that the 

 action is more rapid and complete at higher temperatures i. e., at 35j 

 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 experiment in rooms that it is pos- 

 sible to disinfect the surface of apartments and articles contained in 

 them, under the conditions of temperature and moisture ordinarily 

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

 saturated atmosphere of formaldehyde gas. 



Stahl has shown that bandages and iodoform gauze can be kept 

 well sterilized by placing in the jars containing them pieces of a] 

 preparation of paraforrn aldehyde in tablet form containing 50 per 

 cent, of formaldehyde. The same experimenter has also succeeded 

 in making carpets and articles of clothing 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, Pottevin, and others have | 

 shown that a concentration of yolhro f tne aqueous solution (40 per j 

 cent.), equal to YTTHTO f 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 forms about one-half the strength of pure 

 carbolic acid. 



