THE ALCOHOL TEST IN EELATION TO MILK. 5 



THE ALCOHOL TEST IN RELATION TO FRESH MILK FROM A SINGLE COW 



OR HERD. 



While reviewing the literature on the alcohol test it became evi- 

 dent that the value of the test must be considered from two stand- 

 points: First, its relation to fresh milk from a single cow or small 

 herd, and, second, its relation to mixed market milk. Although 

 our work on this subject deals principally with the relation of the 

 alcohol test to mixed market milk, we feel justified, after a careful 

 survey of the literature, first in briefly discussing the test in its rela- 

 tion to fresh milk from a single cow or herd. 



In the consideration of fresh milk from a single, normal cow we 

 must omit the changes in milk due to bacterial growth and the in- 

 fluences of the changes on the alcohol test. The changes as a result 

 of bacterial activities are of greater importance in the relation of the 

 alcohol test to the mixed market milk and will be discussed later. 



It is evident from the results of other investigators and from our 

 own tests on milk from a few cows that fresh, normal milk occasion- 

 ally coagulates with 68 or 70 per cent alcohol when mixed in equal 

 volumes. Henkel (12) found, after an examination of more than 

 1,600 samples of milk from a single cow, that 6 showed a coagulation 

 with 68 or 70 per cent alcohol. This is a very low percentage of 

 positive results and he concluded that, generally speaking, the milk 

 of a single animal does not coagulate with 68 or 70 per cent alcohol. 

 After an extensive study of the alcohol test Auzinger (2) concluded 

 that the alcohol coagulation of fresh single milk is not so rare as 

 Henkel had observed. Auzinger (2) also found great fluctuations in 

 the alcohol test (70 per cent) with milk from single cows. Occa- 

 sionally milk from the same cow gave a positive test in the morning 

 and not in the evening, or vice versa. The test might be positive 

 one day and not the next, but might reappear on the third day. 

 Sometimes he found that the first and last milk from a single cow 

 showed fluctuations in the alcohol test. Auzinger also found that 

 milk from single quarters may coagulate with alcohol independently 

 of the other quarters, although these cases were rare. He concludes 

 that the alcohol test in normal milk from a single cow is independent 

 of the acidity and when the test is positive it is caused by a change 

 in the milk salts, especially the calcium, in their relation to the milk 

 proteids. His opinion as to the reason for the occasional coagula- 

 tion of fresh, normal milk is strengthened by one of his experiments, 

 in which calcium phosphate was fed to a cow. It was found that the 

 milk from this cow coagulated with a smaller volume of alcohol or 

 with a lower percentage of alcohol than did the normal milk. 



When fresh, normal milk from a single cow coagulates with 68 per 

 cent alcohol it is evidently due to some slight change in the com- 

 position of the milk. What the exact changes are it is impossible at 

 present to state. 



