i8 



QUATERCENTENARY STUDIES IN PATHOLOGY 



volume of carbolic acid performing the same work ; or this multiple may 

 be expressed as the " Carbolic Acid Co-efficient." For example : — 



B. COLI COMMUNIS— 24 HOURS' BROTH CULTURE. 



The multiple here is 10 — i.e., it will require 10 volumes of carbolic 

 acid to perform the work done by one volume of the disinfectant (X) 

 under observation. 



The following experiments were undertaken to test and compare the 

 relative actions of Formaline, Phenol, Corrosive Sublimate, Cyllin, Izal, 

 Sanitas, and Sapo-Cresol. 



Phenol. — Carbolic acid, once the most widely used of disinfectants, 

 has been disparaged in recent years because laboratory tests have 

 demonstrated that it cannot be depended upon to kill spores. A i or 2 

 per cent, solution has no certain effect upon anthrax spores. A 3 per 

 cent, solution requires 7 days, a 4 per cent, solution, 3 days, and a 5 per 

 cent, solution 2 days, to kill anthrax spores. Weaker solutions are 

 effective for non-sporing bacteria. Behring found that \ per cent, 

 solution killed the germs of Cholera, Plague, Typhoid, Diphtheria, and 

 Erysipelas in one hour, while a i to ij per cent, solution would destroy 

 these organisms in one minute. 



Corrosive Sublimate. — The high disinfectant power of perchloride of 

 mercury is well known. It is largely used in surgery, but it is little used, 

 at any rate in this country, for ordinary disinfection. One important 

 objection to its use being its great toxicity. A solution of i in 

 1000 is ample for the destruction of non-sporing bacteria in half-an-hour. 

 Solutions of 1-500 and 1-800 will kill non-sporing bacteria in a short 

 time. For spores, 1-500 solution, with an exposure for one hour, is 

 necessary. Andrewes has pointed out that the resistance of the 

 Staphylococcus pyogenes aureus against mercurial salts is altogether 

 exceptional, but that this resistance does not extend to antiseptics of 



(254) 



