50 
LABORATORY MANUAL 
in tester in pocket provided with corks and whirl for 8 
minutes at a speed of 57 turns of crank per minute. (2000 
R. P. M.) Place tests in rack for 10 minutes and then 
read results direct. 
B. Make a fat test of the milk provided and compare the ratio of 
the casein to fat. 
Note: All operations for the casein test should be as near 70° 
F. as possible. 
Observations: 
Sample 
% casein 
% fat 
Ratio 1 :? 
1 
2 
Conclusions: 
Questions: (1) What is the condition of the casein in normal cow s milk? 
(2) In what manufactured dairy product is casein one of the chief 
constituents? About what per cent? 
(3) Give a formula and explain its use for determining the approxi¬ 
mate protein and casein content of milk, when the lactometer 
is used. 
(4) What are some of the commercial uses of casein? 
References: F. & W. If 257a, 258, 307; Van S. pp. 8-12, 199-200; St. pp. 
318-321. 
