DAIRY HUSBANDRY 
13 
EXERCISE NO. 7 
Object: To study the effect of weak acid on results obtained by the Babcock 
test. 
Procedure: “It is indeed remarkable what slight difference in the specific 
gravity of the acid will make themselves apparent in the work¬ 
ing of the test.” (F. & W. f 75.) 
A. Make each of the following tests in duplicate: 
(1) 17.6 cc. of milk and 17.5 cc. of acid (sp. gr. 1.82-1.83). 
(2) 17.6 cc: of milk and 17.5 cc. of weak acid (sp. gr. 1.78) 1 
part water to 20 parts acid. 
(3) 17.6 cc. of milk and 21-23 cc. of weak acid of test No. 2. 
(4) 17.6 cc. of milk and 17.5 cc. of weak acid heated to 100° F. 
before using. 
Note: For preparing the weak acid see F. & W. f 74. Never 
dilute sulfuric acid by pouring water into it. 
Observations: Record results and observations as follows: 
Sample 
Temperature 
% fat 
Color of fat 
Condition of fat 
Milk 
Acid 
1 
a 
b 
2 
a 
b 
3 
a 
b 
4 
a 
b 
Conclusion: 
Questions: (1) Show by using figures how a 5% reading would be influ¬ 
enced if read at 180° F. instead of at 140° F. 
(2) What precaution should be taken if sulfuric acid is too strong? 
(3) Give 5 reasons why the fat column may be dark in color or con¬ 
tain black spots, or have dark curd directly underneath? 
(4) Give 4 reasons why the fat column may be light in color, or 
contain light spots, or have light curd directly beneath? 
References: F. & W. f 72-79, inclusive; Van S. pp. 43-46; 65-70; Jud. 71; 
St. pp. 118-119. 
