BULLETIN OF THE 



i. 



No. 202 



Contribution from the Bureau of Animal Industry, A. D. Melvin, Chief. 

 May 12, 1915. 



(PROFESSIONAL PAPER.) 



THE ALCOHOL TEST IN RELATION TO MILK. 



By S. Henry Ayers, Bacteriologist, and William T. Johnson, Jr., Scientific Assistant, 



Dairy Division. 



INTRODUCTION. 



The alcohol test as generally used consists in the mixing of equal 

 volumes of alcohol and milk. Usually 2 cubic centimeters of 68 per 

 cent alcohol are added to .2 cubic centimeters of milk and shaken 

 gently in a test tube. The test is considered positive when a precipi- 

 tate is formed, or in other terms, when a coagulum is produced. 

 When a positive test is obtained with fresh milk from a single cow or 

 small herd, it is generally believed that it indicates an abnormal milk, 

 due to physiological or pathological conditions in the cow. A positive 

 test with market milk is supposed to indicate that changes have been 

 produced in the milk as a result of bacterial fermentations. 



According to Fleischmann (ll) 1 the first account of the alcohol 

 test was published by Martina in 1890 in the Deutsche (Berliner) 

 Molkerei Zeitung. It is stated that Martinn used 68 per cent alcohol 

 with equal parts of milk. Hoft (13) in 1898 used the alcohol test to 

 give an idea of the acidity of milk. He found that the higher the acidity 

 the greater the amount of coagulation by alcohol. In the same year 

 Petri and Maaszen (24) made use of the alcohol test to determine the 

 quality of pasteurized milk, and Weber (31) in 1900 studied the alcohol 

 test in relation to the so-called sterilized milk. 



Since 1900 numerous investigators, mostly in Europe, have studied 

 the alcohol test. Of those who have worked with this test Morres is 

 probably its most ardent supporter. He strongly advocates the 

 alcohol test in combination with the alizarin test, which he calls the 

 alizarol test. This test will be described later. Morres and the 

 other advocates of the alcohol test claim that it is of great value, 

 since it affords a simple and quick means of determining the condition 

 and keeping quality of milk. 



In this country the alcohol test is used by only one large company 

 which manufactures milk powder. Any milk which shows a precipi- 



1 See list of citations to literature at end of bulletin. 

 82832°— Bull. 202—15 1 



