76 BACTERIOLOGY 



favorable results. The substance is not extensively employed 

 and further investigation is necessary to dermine its true 

 value. 



Silver Nitrate.- — This salt probably occupies the position next 

 to the bichloride of mercury in germicidal power. Behring claims 

 it to be superior to bichloride of mercury in albuminous fluids. 

 The anthrax bacillus is killed by a solution of 1-20,000 after two 

 hours' exposure. At least forty-eight hours' exposure to a i-io,- 

 000 solution is required to kill the spores of anthrax. It is very 

 irritating, an4 possesses strong affinities for chlorides, forming 

 with them insoluble chloride of silver, a salt without germicidal 

 value. For these reasons the use of silver nitrate is limited. In the 

 solutions usually employed for douching the cavities of the body- 

 the available silver nitrate is immediately converted into the 

 insoluble chloride, and little if any germicidal action takes place. 

 To this fact may be ascribed the vwrying clinical results reported.; 



Many proprietary silver compounds are on the market, in- 

 troduced to replace the nitrate and its objectionable features. 

 The most important are protargol and argyrol, organic silver 

 combinations. They do not combine with chlorides, are less 

 irritating than the nitrate and, not coagulating albumin, they 

 ' possess greater penetrating power. 



Organic Poisons. — Carbolic acid is one of the most important 

 and most widely used disinfectants. It is usually employed in 

 strengths of from i to 5 per cent. A 3 per cent solution will 

 sometimes kill the spores of anthrax after two days' exposure. 

 In the absence of spores, the anthrax bacillus is destroyed by a i 

 per cent solution in one hour. The less resistant pus cocci are 

 destroyed rapidly by a 2 per cent solution. Combination with an 

 equal proportion of hydrochloric acid enhances the efficacy of 

 carbolic acid to a marked extent. This is due to the prevention 

 of albuminous combinations, thus allowing greater penetration 

 of the disinfectant. 



Many other substances closely related to carbolic acid are 

 used and possess marked germicidal properties. Among them 



