28 BULLETIN 661, U. S. DEPARTMENT OF AGRICULTURE. 
Table 5. — Comparison of calculated and actual fat content of casein. 
Fat 
content of 
butter- 
milk. 
Fat content of casein. 
Sample No. 
Calculated. 
By ether 
extraction. 
56.3 
Per cent. 
.07 
.18 
.20 
.16 
.28 
.89 
.015 
.35 
.60 
.07 
.01 
.13 
.04 
.02 
.19 
Per cent. 
2.31 
5.94 
6.60 
5.28 
9.24 
29.37 
.495 
11.55 
19. SO 
2.31 
.33 
4.29 
1.32 
.66 ■ 
6.27 
Per cent. 
6 36 
56.4 
9.89 
56.9B 
23 83 
56.10A : 
56.12A 
56.13A 
56.14 
6.31 
8.71 
21.27 
.93 
56.15A 
56.16B 
12.63 
14. 40 
56.17B 
9.67 
56.20A 
4.29 
56.23A 
56.25A 
9.52 
3.98 
56.30A 
7.53 
56.35A 
4.18 
All analyses of casein samples were made by R. H. Shaw and E. F. Deysher, of the Dairy Division. 
Analyses of samples of domestic and foreign skim-milk casein and 
of buttermilk casein appear in Table 6 and show the difference in 
chemical composition. The buttermilk samples, made from what 
would be regarded as the usual run of buttermilk in creameries re- 
ceiving a good grade of cream, show a marked increase in fat, as 
was to be expected. 
Table 6. — Comparative analyses of skim-milk and buttermilk casein. 
Origin. 
Chemical analysis. 
Sample No. 
Mois- 
ture. 
Fat. 
Ash. 
56.40... 
Per cent. 
7.80 
8.28 
7.95 
6.44 
8.43 
7.74 
7.65 
6.68 
6.82 
5.86 
6.42 
Per cent. 
0.60 
0.93 
0.66 
1.04 
0.75 
0.93 
6.54 
5.00 
9.52 
5.62 
5.82 
Per cent. 
2.80 
56.41 
do 
2.44 
56.43... 
56.44 
Domestic sMm milk 
3.69 
56.45 
French skim milk 
1.86 
56.14 
Domestic skim milk 
1.14 
56.10B 
Buttermilk. . . , 
0.99 
56.22.. 
do 
1.30 
56.23A 
do 
0.60 
56.35C 
... .do 
.0.76 
56.37... 
.do... 
1.19 
METHODS OF DETERMINING QUALITY OF CASEIN. 
In order to determine factors having a direct bearing upon the 
quality of buttermilk casein and the conditions requisite to the man- 
ufacture of a product of the best practical value, a study of the 
solubility, adhesiveness, and general working properties of various 
lots of casein made under varying conditions was undertaken. But- 
termilk from pasteurized sweet cream ripened to an acidity of from 
0.40 to 0.G5 per cent was used in the investigational work, and no 
