DAIRY HUSBANDRY 
EXERCISE NO. 31 
Object: To determine the adulteration of an unknown sample of milk. 
Procedure: The table of adulteration which follows is to be compared 
with the control sample if one is provided or it may be used 
with the factors usually assigned to normal milk. 
Normal 
Watered 
Skimmed 
Skimmed and 
W atered 
Fat 
3% + 
Lower 
Lower 
Lower 
Sp. Gr. of 
milk 
1.029—1.035 
Lower 
Higher 
Normal—higher 
or lower 
% S. N. F. 
8.5% + 
Lower 
Nor. or higher 
Lower 
% T. S. 
11.5% + 
Lower 
Lower 
Lower 
Sp. Gr. of 
milk solids 
1.25—1.34 
Normal 
Higher 
Higher 
A. Make a lactometer and fat test of the control sample and in¬ 
clude all calculations. 
B. By using the Babcock test and the lactometer, analyze the 
“adulterated” sample of milk and report the adulteration. 
C. Calculate the per cent reduction of SNF by the following for¬ 
mula: 
SNF in control—SNF in adulterated 
D. 
-xioo. 
SNF in control 
Calculate the per cent reduction of fat by the following for¬ 
mula: 
% Fat in control—% in adulterated 
--xioo. 
% Fat in control 
If the sample is watered only the two results obtained should 
correspond. If the sample is skimmed only, no appreciable 
answer will be obtained from the 1st formula. Usually the 
answer is negative. If an appreciable answer is obtained from 
the first formula, and if the result from the last formula is 
greater than that from the first, the sample is Watered and 
Skimmed. The difference between the two results gives the % 
of skimming. 
