44 CHEESE MAKING. 
91. Effect of Water in Milk. 
Diluting milk with water retards coagulation. 
Experiment (a). Make a careful rennet test of a sample of 
milk. Next take one part of water and three parts of the milk 
in question. Mix them and then make a rennet test of the 
mixture. 
Experiment (b). Repeat the experiment with one part of 
water and two parts of milk. 
Experiment (c). Repeat the experiment with one part of 
water and one part of milk. Can you determine any law gov- 
erning the rate of coagulation in relation to the amount of water 
present? Try these experiments with milks of different acidity. 
92. Effect of Salt (NaCl). 
Salt in the milk checks the action of rennet, five per cent 
stopping it altogether. 
Expertment (a). Make a rennet test of a sample of milk, 
and record the result. Now add one per cent of salt by weight 
and make a careful rennet test. How does the salt affect the 
test? Try the same experiment with two, three, four and five 
per cent of salt in the milk. 
93. Effect of Temperature. 
Raising the temperature up to a certain point hastens, and 
lowering it retards, rennet action. 
Experiment (a). Make a rennet test at the standard tem- 
perature of 86° F., and record the result in your notebook. Now 
make tests at 95°, 100°, 110°, 120°, 180° and 140°. 
Experiment (b). Make a test at 86° and then try tests at 
80°, 70°, 60°, 50° and 40°. If much time is consumed in mak- 
ing the tests, the student should make occasional tests at 86° F. 
to detect the rate of ripening of the milk. 
94. Effect of Anaesthetics. 
Anesthetics, like chloroform and ether, suspend protoplas- 
mic action but do not affect enzymes. In this way it is possible 
to distinguish between organized and unorganized ferments. 
Experiment (a). Make a rennet test of a sample of milk 
and note the number of seconds required. Now add about 8 per 
cent of chloroform to the sample and shake it in a bottle or 
