New York AGRICULTURAL EXPERIMENT STATION. 97 
the usual way and the curd allowed to drain. In the experiments 
tabulated below, we used in each case 20 pounds of pasteurized 
separator skim-milk. After the addition of acid, the curd was 
allowed, in several cases, to stand 15 to 45 minutes before remoy- 
ing the curd from the whey, but usually there was no advantage 
in waiting this length of time. 
TaBLE 1V.—MANUFACTURE OF CoTTAGE CHEESE By USE oF ARTT- 
FICIAL ACIDS. 
Temp. of ° a 
No. of milk when Kind and Character of Character of | Moist- 
experi- matdaray amount of curd aahe ure in 
ment. edded acid used. a we cheese. 
Degrees F. Lactic. Per ct. 
1 90° 0.4 per et Soft and slimy Sep., slow a 
2 90° 0.5 per et Softer than 3 Clear 70.9 
3 90° 0.6 per ct Firm and dry Clear 64.7 
4 152. 0.6 per ct. | Good Clear 74.6 
a 105° 0.6 per ct. | Hard, dry Clear 60.4 
6 105° 0.8 per ct. | Tough, dry Clear 62.0 
7 105° 1.0 per ct Tough, dry Clear, sour 51.8 
Hydrochloric. 
8 752 0.25 per et. | Good Clear WSiou 
9 Haye 0.25 per ct. | Good Clear 76.4 
The following statements summarize the data embodied in 
Table IV :— 
(1) Amount of acid used.—When less than 0.5 per ct. of 
lactic acid was used, the resulting curd was soft and slimy, and 
the whey separated slowly and incompletely. When more than 
0.6 per ct. of lactic acid was used, the curd was too dry. The 
use of 0.25 per ct. of hydrochloric acid gave satisfactory results. 
We have previously*® called attention to the fact that mineral 
acids are required in smaller amounts than organic acids to pre- 
cipitate casein completely. 
(2) Effect of temperature——When the milk was at a tempera- 
ture of 105° F. (40° C.) at the time the acid was added, the whey 
was clear and separated rapidly, but the curd was much too dry 
and hard. Good results were obtained at 80° F. (32° C.), when we 
used 0.5 per ct. of lactic acid, while with 0.6 per ct. the curd 
was too dry. The temperature of 75° F. (24° ©.), with 0.6 per 
ct. of lactic acid gave good results in every respect. With 0.25 
per ct. of hydrochloric acid, a temperature of 75° F. (24° C.) 
Bulletin No. 14, p. 67, (1902). 
7 
