96 Report oF THE CHEMIST OF THE 
varied from 2 to 2.5 per ct. From 17 to 19 per ct. of the nitro- 
gen of the milk went into the whey. Some casein dilactate in 
the form of fine particles of curd, is usually lost in the operation 
of removing the whey from the curd. 
(6) Separation of whey from curd—lt is a matter of impor- 
tance in the manufacture of cottage cheese that the whey shall 
separate readily from the curd and shall be clear. Milky whey 
means loss of solids and usually accompanies a slow separation 
of whey. For effecting satisfactorily the separation of whey 
from curd, milk is generally heated to a temperature considerably 
above that employed in souring the milk. In our experience, 
we have found the whey to separate readily and clear when the 
souring has been carried on at a temperature of about 70° F. 
(21° C.) and after complete coagulation and cutting, the tem- 
perature has been gradually raised to 85° to 90° F. (29° to 
32° C.), and held at that temperature for not less than fifteen 
minutes. 
THE MANUFACTURE OF COTTAGE CHEESE BY THE DIRECT ADDITION 
OF AN ARTIFICIAL ACID TO MILK. 
Since the coagulation of milk-casein can be readily accomplished 
by adding any common acid directly to milk, it occurred to us that 
some practical application could be made of this fact in the 
preparation of cottage cheese. We first used lactic acid, adding it 
to milk in the proportions of 0.4, 0.5, 0.6, 0.8 and 1 per ct. by 
weight of the milk used. Hydrochloric acid was also used in pro- 
portion of 0.25 per ct. The acid was always diluted with 8 to 
10 times its volume of water before being added to the milk. The 
procedure was to bring the milk to a certain temperature and then 
to add the diluted acid to the milk, mixing it through the mass 
of milk as quickly and completely as possible. The mixing not 
only distributes the acid but prevents the curd forming in a solid 
mass or in large lumps. The stirring is continued until the whey 
separates clear. The curd separates in flocculent form and does 
not need any additional cutting or breaking. When small quan- 
tities of milk are used, the whole mass can be put on a strainer 
and allowed to drain. In the case of large quantities of milk, the 
curd can be allowed to settle in the vat and the whey run off in 
