Chemical and Physical Papers. 39 



DISINFECTANTS. 



Having been appointed as one of the members of a committee 

 to report on standards for disinfectants, it may be in place to call 

 attention to the ruling of the Kansas Board of Health, which was 

 based on the report of the committee. The tentative standard 

 adopted by this board reads as follows : 



A substance may be said to be a disinfectant or germicide, or to act as 

 a germicide, when under stated conditions of concentration, temperature, 

 humidity, etc., it is able to kill any non-spore-bearing bacterium patho- 

 genic to man within six hours. Unless otherwise expressly stated, temper- 

 ature and other atmospheric conditions usually found in living rooms will 

 be understood. 



Within the meaning of this definition the terms "germicide" and "dis- 

 infectant" are used interchangeably to mean substances that actually de- 

 stroy, and not merely inhibit the growth of bacteria. 



Various methods have been used for standardization of disin- 

 fectants, beginning with Pringle (1732), who attempted to arrest 

 putrefaction by the addition of various substances, and including 

 Kock's "thread method" (1881), which was the first systematic 

 test for the germicidal power of disinfectants. Kock's method was 

 followed by the Rideal and Walker or "drop method" (1903) and 

 its various modifications. 



After consideration of all these methods of different workers, 

 the committee on standardization of disinfectants recommended 

 for adoption as the standard methods the Hygienic Laboratory 

 phenol coefficient methods, as devised by Doctors Anderson and 

 McClintic and published in Hygienic Laboratory Bulletin No. 82. 



To secure uniformity, the third distillate of Merck's Silver La- 

 bel Phenol was used in making the 5 per cent stock dilutions, from 

 which all other phenol dilutions were made. 



To obtain a culture of even resistance, it was recommended to 

 use B. typhosus from a 30-day at 20° C. stock culture on standard 

 infusion agar. Transplants are made at intervals of twenty-four 

 hours in usual manner. The procedure is, briefly, as follows: 



Since most disinfectantshave a coefficient of 1 or over, a stock 

 dilution of 1-100 is made of the disinfectant, but for those having 

 a coefficient less than one a 1-20 is used. These dilutions are meas- 

 ured by means of pipettes into^sterile glass-stoppered graduated 

 cylinders containing sterile distilled water, and made up to the 

 mark with same. From these stock dilutions the necessary dilu- 

 tions for teats are made, using sterile pipettes of several sizes, and 

 adding the required amount of the stock dilution and distilled 

 water from sterile lead-foil-topped flasks to lead-foil-topped sterile 

 bottles. 



