Contamination of Milk. 51 



though Bitter states that 50,000 organisms per cc. should 

 be a maximum limit in milk intended as human food. 

 As a result of a study of the supply of New York city, 

 Park believes it is possible for a milk producer, without 

 adding materially to his expense, to secure milk which 

 when first drawn will not contain on an average more 

 than 30,000 bacteria in hot weather and 25,000 in cold 

 weather. If such milk is chilled immediately to 50 F., it 

 will not contain more than 100,000 per cc. in twenty-four 

 hours. Rochester, New York, has already tried the en- 

 forcement of a standard (100,000 per cc.) with good re- 

 sults it is claimed. The practical difficulties to contend 

 with in establishing a milk standard based upon a quanti- 

 tative bacterial determination are such as to render its gen- 

 eral adoption extremely problematical. 



Acid test. It would seem that some other test which 

 can be more easily employed, even though it might not be 

 susceptible to an equal degree of accuracy, would be pref- 

 erable. Such a test is to be found in the acid test which 

 measures the acidity of the milk in question. There are 

 of course organisms to be found in milk that do not pro- 

 duce acid, and therefore it might be thought that the 

 presence of such would militate against the accuracy of 

 .such a test; but under normal conditions, the lactic acid- 

 producing organisms find in milk so congenial a sub- 

 stratum for their development, that in the great majority 

 of cases, the determination of the acid indicates the man- 

 ner in which milk has been handled. High acidity is either 

 due to old milk (long period of incubation) or insufficient 

 cooling (rapid incubation). Either of these conditions 

 permits of the accumulation of bacterial life, and therefore 

 impairs the quality of the milk. The determination of the 



