THE ALCOHOL TEST IN RELATION TO MILK. 7 
cow might reveal some pathological condition, or there might be 
some physiological reason for a slight variation in the composition 
of the milk. If the test were performed on the milk from a few cows 
a positive reaction might be caused, as Auzinger (3) believes, by the 
mixing of milk which is changed by physiological or pathological 
conditions with milk from normal cows. If there were a large per- 
centage of abnormal milk which gave an alcohol test with a coagula- 
tion with large flakes, the mixed milk might show a positive alcohol 
test in which the coagulation would be in the form of small flakes. 
When mixed milk from a large number of sources gives a positive 
alcohol test it must be interpreted in an entirely different manner, 
and this leads us to another phase of the subject. 
THE ALCOHOL TEST IN RELATION TO MARKET MILK. 
Since 1900 a considerable number of papers have appeared on the 
use of the alcohol test in its relation to market milk. According to 
Kirchner (15), Morres in 1905 showed that the alcohol test was of 
value for determining the keeping quality of milk and indicating its 
acidity. Reiss (26) in 1906 pointed out the practical value of the 
test, and Morres (18) again in 1909 showed the value of the alcohol 
test as a means of determining the keeping quality of milk. He added 
2 c.c. of milk to 2 c.c. of 68 per cent (by volume) alcohol, and states 
that if the milk coagulates with alcohol then decomposition has 
already started and the extent is shown by the size of the flakes. 
If the precipitate is in fine flakes then the acidity corresponds to 
4 degrees Soxhlet; however, the coagulation may not be due to an 
increase in acidity, but may be due to the action of rennet-forming 
bacteria. In later work Morres has combined the alcohol and 
alizarin tests. This will be discussed later. Morres considers that 
the coagulation of mixed market milk is due largely to the formation 
of acid or the action of rennet-forming bacteria or to a combination 
of both. Henkel (12) concludes from his work that the alcohol test 
does not afford a proper means for determining acidity, but that the 
value of the test lies in the fact that it gives a knowledge of the souring 
and other changes in the properties of milk or in variations from the 
normal properties which the acid test does not show. Other investi- 
gators believe that the alcohol test is of value only as a preliminary 
test. Fendler and Borkel (10) after a large number of tests to 
determine the relation of the acidity of milk to the alcohol test con- 
cluded that the double test with 70 per cent alcohol was not a proper 
criterion for the freshness of market milk, including infants' milk 
and superior grades of milk. They state that the double test using 
50 per cent alcohol is suitable as a preliminary test for food in- 
spectors, but the milk should be submitted to further tests. These 
authors also found that no consistent relation existed between the 
