titiSTR UOTION OF BACTERIA S Y CHEMICALS. 159 



exposed for ninety-six hours in a disinfecting chamber 

 to the action of SO 2 in the proportion of from 4 to 6 

 per cent, by volume were not destroyed. In the ab- 

 sence of spores, however, the anthrax bacillus in a 

 moist condition, attached to silk threads, was found 

 by Sternberg to be destroyed in thirty minutes in an 

 atmosphere containing 1 volume per cent. As the re- 

 sult of a large number of experiments with SO 2 as a 

 disinfectant it has been determined that an " exposure 

 for eight hours to an atmosphere containing at least 

 4 volumes per cent, of this gas in the presence of moist- 

 ure 77 will destroy most if not all of the pathogenic 

 bacteria in the absence of spores. 



Peroxide of Hydrogen (H 2 O 2 ) is an energetic disin- 

 fectant, and in 2 per cent, solution (about 40 per cent, 

 of the ordinary commercial article) will kill the spores 

 of anthrax in from two to three hours. A 20 per cent, 

 solution of a good commercial hydrogen peroxide solu- 

 tion will quickly destroy the pyogenic cocci and other 

 spore-free bacteria. It combines with organic matter, 

 becoming inert. It is prompt in its action and not 

 poisonous, but apt to deteriorate if not properly 

 kept. 



Chlorine is a powerful gaseous germicide, owing its 

 activity to its affinity for hydrogen and the consequent 

 release of nascent oxygen when it comes in contact with 

 micro-organisms in a moist condition. It is, there- 

 fore, a much more active germicide in the presence of 

 moisture than in a dry condition. Thus, Fischer and 

 Proskauer found that dried anthrax spores exposed for 

 an hour in an atmosphere containing 44.7 per cent, of 

 dry chlorine were not destroyed; but if the spores were 

 previously moistened and were exposed in a moist 



