170 TWENTY-FIFTH ANNIVERSARY REPORT. 
(3) The fat and casein increase in about the same proportion 
from month to month, leaving out the abnormal month of August. 
(4) The whey solids (albumin, sugar, etc.) tend to decrease as 
the period of lactation advances. 
2. THE COMPOSITION OF MILK IN RELATION TO THE YIELD OF CHEESE. 
The following facts have been firmly established by our investi- 
gations: 
(1) Yield of cheese variable with different milks— The amount 
of cheese made from 100 pounds of milk varies in the case of dif- 
ferent milks. Such differences in yield are due to differences in 
the composition of milk. 
(2) Yield of cheese dependent upon certain constituents of milk. 
— It has been shown by our results that the yield of cheese depends 
most largely upon two milk constituents, fat and casein. 
The milk solids may be roughly divided into two general classes: 
(a) cheese-producing and (b) whey solids. The former includes 
fat, casein and insoluble ash; the latter, albumin, sugar and soluble 
ash constituents. A little fat and casein go into whey, while a small 
amount of albumin and sugar goes into cheese. Most of the water 
goes into whey. On an average, 49.1 per ct. of the milk solids goes 
into whey and 50.9 per ct. into cheese (Tables I and II). 
(3) Amounts of milk-fat and milk-casein in different milks.— 
Milk-casein varies in amount in different milks, but not as much 
as fat does. ‘The following table illustrates the relations of fat and 
casein in cheese-factory milk.1¢ 
TABLE IJJ.— AmMouNTS oF FAT AND CASEIN IN Factory MILK. 

Fat Casein 
in in 
enilk. milk. 
Per ct. Per ct. 
3.00 2.10 
3.25 2.20 
3.50 2.30 
3.75 2.40 
4.00 2.50 
4.25 2.60 
4.50 2.70 


SSS a ee naa 
* Bul. 110; ‘Rpt. 15:66-106 (1896). 
