ACTION OF ACIDS AND ALKALIES. 179 



Benzoic Acid. According to Miquel, this acid restrains the de- 

 velopment of putrefactive bacteria when present in bouillon in the 

 proportion of 1: 909. In the proportion of 1 : 2,000 it retards the de- 

 velopment of anthrax spores (Koch). 



Formic Acid. The typhoid bacillus is restrained in its growth by 

 0.25 per cent, and is killed in five hours by 0.35 per cent, the cholera 

 spirillum by 0.22 per cent (Kitasato). 



Tannic Acid. A solution of one per cent kills Micrococcus Pas- 

 teuri in the blood of a rabbit in half an hour (Sternberg). A five- 

 per-cent solution failed in ten days to destroy anthrax spores (Koch). 

 A twenty-per-cent solution failed in two hours to destroy the vitality 

 of spores of the anthrax bacillus or of Bacillus subtilis (Abbott). 

 Micrococci are destroyed by 1 : 400, and 1 : 800 failed (Abbott). A 

 twenty-per-cent solution has no effect upon the virus of symptomatic 

 anthrax (Arloing, Cornevin, and Thomas). A solution of 1.66 per 

 cent kills the typhoid bacillus in five hours, and 1.5 per cent the 

 cholera bacillus in the same time (Kitasato). It restrains the devel- 

 opment of putrefactive bacteria in the proportion of 1 : 207 (Miquel). 



Tartaric Acid. A twenty-per-cent solution of this acid fails, 

 after two hours' exposure, to destroy the spores of Bacillus anthracis 

 or Bacillus subtilis. Micrococci are killed by two hours' exposure in 

 a solution containing 1 : 400 (Abbott). 



Malic Acid. This was found by Kitasato to correspond with 

 citric acid in its germicidal power. 



Valerianic Acid. A five-per-cent solution in ether failed in five 

 days to destroy anthrax spores (Koch). 



Oleic Acid. A solution of five percent in ether does not destroy 

 anthrax spores in five days (Koch). 



Thymic Acid. In the proportion of 1 : 500 this acid prevents the 

 putrefactive decomposition of beef tea (Miquel). 



Butyric Acid. Five days' immersion in this acid failed to de- 

 stroy anthrax spores (Koch). 



Arsenious Acid. A one-per-cent solution destroys the vitality 

 of anthrax spores in ten days, but failed to do so in six days (Koch). 

 In the proportion of 1 : 166 it prevents putrefactive changes in bouillon 

 (Miquel). 



Gallic Acid. Abbott found this acid to destroy the bacteria in 

 broken-down beef tea in the proportion of 2.37 per cent, but it failed 

 to destroy anthrax spores in two hours in the same proportion. Mi- 

 crococci were killed in two hours by 1 : 142, while 1 : 250 failed. 



ALKALIES. 



Potassium Hydroxide, KHO. In the writer's experiments aten- 

 per-cent solution of caustic potash was fatal to pus cocci, and an 



