New York Agricultural Experiment Station. 193 



varying in different cases from 85° C. to 98° C. (185° F. to 

 208° F.). Then, in order to prevent possible contamination by 

 the entrance of enzyme-producing organisms, the milk, after 

 being heated and cooled, has been treated with 3 to 5 per ct. 

 of chloroform by volume, previous to being made into cheese. 

 The heating of milk to the temperature stated diminishes the 

 readiness and completeness with which it is coagulated by rennet- 

 extract, but the power of prompt coagulation by rennet can be 

 restored by the addition of calcium chloride or carbon dioxide 

 or any ordinary acid. In thus eliminating other factors of 

 cheese-ripening than rennet-enzyme, we necessarily produce con- 

 ditions that do not exist in normal cheese-making, such as (i) 

 heated milk, (2) absence of milk-enzymes, (3) the use of calcium 

 chloride or carbon dioxide, and (4) absence of enzyme-forming 

 and acid-forming organisms. In a study carried on under such 

 conditions, we cannot expect our results to be entirely com- 

 parable with results obtained under normal conditions; but we 

 can secure data that enable us to determine the ability of the 

 rennet-enzyme to cause proteolytic changes under the conditions 

 of experiment employed. Later, we will inquire as to whether 

 the introduction of such unusual conditions seriously afifected the 

 value of the results obtained, in their application to the process 

 of normal cheese-ripening. 



GENERAL OUTLINE OF EXPERIMENTAL WORK. 



For each cheese made, we used from 40 to 75 pounds of 

 normal milk, making a cheese adapted in size to the most con- 

 venient conditions of our work. Chloroform, when used, was 

 introduced into the milk as soon as the milk had been heated 

 to 85° C. to 98° C. (185° F. to 208° F.) and cooled to 29° C. 

 (84° F.). The process of making cheese was then carried out 

 in the usual manner. At the time of adding chloroform, samples 

 of milk were taken out and carefully kept for chemical and 

 bacteriological examinations, in order to ascertain whether any 

 proteolytic enzymes remained active. 



In experiments 44 to 47, calcium chloride was added tO' the 

 milk to restore its coagulable power with rennet. In doing this, 

 a solution was made containing 200 grams of pure calcium 



