+ 
New YorK AGRICULTURAL EXPERIMENT STATION. at 
Just how much deduction should be made in case of cream, it 
is more difficult to say. For ordinary work in creameries, such 
distinctions are not essential. . : 
Therefore, in the results given in Table I, we have not stated 
the absolute amount of lactic acid present in the cream; but 
the results, in the form given, are more readily comparable with 
the results obtained in creamery work. 
THE RELATION OF CALCIUM CASEIN, CASEIN AND 
CASEIN LACTATE TO THE PROTEIDS OF BUTTER 
AND BUTTERMILK. 
The curd present in butter is casein lactate, when the amount 
of lactic acid formed in cream ripening exceeds 0.5 per ct. In 
butter made from cream ripened so as to contain less than 0.5 
per ct. of acid, the same compound of casein is apt to be present 
ultimately in the butter, especially if buttermilk is left in the 
butter to any extent; because the milk-sugar, present in the but- 
termilk remaining in the butter, is changed in time to lactic acid, 
which acts upon any calcium casein or free casein in the butter, 
producing finally the compound usually present in butter made 
from well-ripened cream. 
In butter made from sweet cream; we find in the butter essen- 
tially calcium casein with, perhaps, some free casein. With 
sufficient milk-sugar incorporated in such butter through the 
presence of buttermilk, we may have at different times any one, 
or a mixture, of the compounds of casein, as follows :—(1) cal- 
cium casein, (2) calcium casein and free casein, (3) casein and 
casein lactate, and (4) casein lactate. It is hardly probable 
that we should often find calcium casein alone in sweet-cream 
butter, as it is commonly made; though it would be possible to 
* make the butter so that it would contain only calcium casein. 
In ordinary sweet-cream butter, when fresh, we commonly find a 
mixture of the two forms, calcium casein and free casein. Later, 
after the formation of more lactic acid, we may have free casein 
alone, which with increasing amounts of lactic acid will be grad- 
ually changed into casein lactate, the form commonly present in 
commercial butter made from ripened cream. 
The amount of milk-albumin in normal butter is very minute 
under any conditions. 
