IX. 

 ACTION OF ACIDS AND ALKALIES. 



Sulphuric Acid, H,SO 4 . The experiments of Koch (1881) 

 showed that anthrax spores were still capable of growing after ex- 

 posure in a one-per-cent solution of sulphuric acid for twenty days. 

 In the writer's experiments (1885) a four-per-cent solution failed to 

 destroy the spores of Bacillus subtilis in four hours, and an eight- 

 per-cent solution was found to be required for the sterilization of 

 culture fluids containing spores ; but the multiplication of the bacte- 

 ria of putrefaction was prevented by the presence of this acid in a 

 culture solution in the proportion of 1 : 800. Pus micrococci were 

 destroyed by exposure for two hours in a solution containing 1 : 200. 



The experiments of Boer show that there is a considerable differ- 

 ence in the resisting power of different pathogenic bacteria. The 

 time of exposure being two hours, cultures in bouillon twenty-four 

 hours old gave the following results : 



Leitz, in his studies relating to the bacillus of typhoid fever, 

 reports the following results : The dejections of typhoid patients, 

 i nixed with an equal proportion of the disinfecting solution, were 

 .sterilized by a five-per-cent solution of sulphuric acid in three days. 

 A pure culture was sterilized in fifteen minutes by two per cent, and 

 in liv> minutes by five per cent. 



Sulphurous Acid, H.SO,. In the writer's experiments (1885) 

 micrococci were destroyed in two hours by 1 : 2,000 by weight of SO, 

 added to water. Kitasato found that solutions of sulphurous acid 

 m the proportion of 0.28 per cent killed the typhoid bacillus, and 

 <>. 1 48 per cent the cholera spirillum. De la Croix found that one 



