STANDARDIZATION OF DISINFECTANTS 



243 



representing the degree of dilution of the weakest strength of the 

 phenol control that kills within the same time. The same is done 

 for the weakest strength that kills in 15 min. The mean of the two 

 is the coefficient. The method of determining the coefficient will 

 be seen in Table III. 



TABLE III 



Name, "A." 



Temperature of medication, 20 C. 



Culture used, B. typhosus; 24 hr.; extract broth filtered. 



Proportion of culture and disinfectant, o.i cc. + 5 cc. 



Organic matter, none; kind, none; amount, none. 



Subculture media, standard extract 'broth. Reaction, 



10 cc. 



Date: May 18, 1913. 



i-5; quantity in each tube, 



To Determine the Comparative Cost per Unit of Efficiency. 



When bids are solicited for supplying disinfectants they should 

 3e required to be made so as to show the comparative cost per 

 coo units of efficiency of the disinfectant as compared with 100 

 inits of pure phenol. It is manifestly cheaper to purchase a 

 17 



