DISINFECTION, STERILIZATION AND ANTISEPSIS. 249 



apparently efficacious. Thus anthrax spores will not grow 

 out in culture media when they are exposed for even a few 

 minutes on silk threads to the action of corrosive sublimate 

 solution of the strength of y^j- per cent, and then washed thor- 

 oughly in water and rinsed in alcohol; but Geppert showed 

 that the spores so treated were only apparently killed, for it took 

 twenty hours, exposure to corrosive sublimate solution of this 

 strength where the spores were not dried on silk threads, but 

 suspended in water, and where the last trace of corrosive sub- 

 limate was removed by treatment with ammonium sulphide. 

 It is claimed that its affinity for albuminous bodies and the 

 readiness with which it combines with such substances detract 

 from its value for some purposes. On the other hand, many 

 observers claim that the albuminous combinations formed 

 under such circumstances are soluble in an excess of albuminous 

 fluid, and that its value as a germicide is not affected thereby. 

 To obviate this possible difficulty it is customary in practice 

 to combine the bichloride of mercury with some substance 

 that will prevent the precipitation of the mercury-salt by al- 

 bumin. For this purpose 5 parts of any one of the following sub- 

 stances to I part of bichloride of mercury may be used — hydro- 

 chloric acid, tartaric acid, sodium chloride, potassium chloride, 

 or ammonium chloride. A very practical stock-solution for 

 laboratory purposes has the following composition: 



Hydrochloric acid lOO c.c. 



Bichloride of mercury 20 grams. 



Five c.c. in a liter of water makes a solution of about i-iooo strength. 



Mercuric Iodide. — An extremely high antiseptic value has 

 been placed on this substance by Miquel, who claims that the 

 most resistant spores are prevented from developing in a cul- 

 ture-medium containing 1-40,000. In combination, as potas- 

 sio-mercuric iodide, it has been used in soaps (McClintock) 

 with very favorable results. The substance is not extensively 



