ACTION OF ACIDS AND ALKALIES. 181 



killed by three successive applications. Iii the writer's experiments 

 (1885) the typhoid bacillus and Staphylococcus pyogenes aureus were 

 killed in two hours by a solution containing 1 : 40 of calcium oxide, 

 and 1 : 80 failed. Spores of the anthrax bacillus and of several other 

 spore-forming species were not killed by two hours' exposure to a 

 milk of lime containing twenty per cent of calcium oxide. 



Potash Soap has been shown by Jolles (1895) to have considerable 

 germicidal value. In experiments with a soap containing 67.44 

 per cent of fat acids, 10.4 per cent of combined alkali, and 0.041 

 per cent of free alkali, the following results were obtained: The 

 typhoid bacillus was destroyed at 18 C. by a one-per-cent solution 

 in twenty-four hours; by a six-per-cent solution in thirty minutes. 

 The Bacillus coli communis required somewhat stronger solutions or 

 longer exposure eight-per-cent solution required thirty minutes. 

 These experiments show that scrubbing with soap and water is a 

 reliable method of disinfecting surfaces. Solutions of potash com- 

 mon lye or of soda also are useful for certain purposes in domes- 

 tic disinfection, and scientific researches justify the continued use of 

 the cleansing methods which have heretofore been in use by careful 

 housewives. 



