230 BACTERIOLOGICAL METHODS 



Diseases may enter the pickling vats and ruin the entire contents 

 within a short time. "Hard cider" is apple wine or cider in 

 which the alcohol has been largely changed into acetic acid by the 

 My coder ma aceti, forming cider vinegar. Cider vinegar in turn 

 may be invaded by bacteria which decompose the acetic acid 

 (Bacillus xylenum). 



22. Standardization of Disinfectants 



The success in modern surgery, preventive medicine and 

 sanitation is based upon the use of disinfectants. This state- 

 ment indicates the importance of disinfectants as articles of com- 

 merce, suggests the necessity of adequate supervision of the manu- 

 facture and commercial handling of these substances and points 

 out the necessity of guarding against adulteration and misrep- 

 resentation. A vast array of so-called antiseptics have been 

 placed on the market, the manufacturer claiming therefor 

 properties which they do not possess. These fraudulent and 

 exaggerated claims have impelled investigations of the marketed 

 disinfectants with a view to determining their true merit. 



Methods for standardizing disinfectants on the basis of 

 their power to kill or destroy bacteria have been proposed by 

 various investigators, some of which have proven quite satis- 

 factory. The Rideal- Walker method and the Lancet method of 

 England and the Anderson-McClintic method of the U. S. Public 

 Health Service appear to find most favor, the latter method 

 being a modification of the two former. In the Rideal- Walker 

 and Anderson-McClintic methods the test organism used is the 

 typhoid bacillus, exposing definite quantities of pure cultures of 

 this organism to varying quantities of the disinfectant to be 

 tested in order to ascertain the killing strength as compared 

 with the standard which is pure phenol. The method is rather 

 complicated and demands great care and precision in technique 

 in order that the results may be reliable and uniform in the dif- 



