TESTS USED IN CHEESE-MAKING 431 



The operation of conducting this test is as follows : 

 Measure with the pipette i cc. of the rennet-extract 

 used and empty it into the ounce bottle, previously 

 half filled with clean, cold water. Rinse the pipette 

 two or three times by drawing water into it from the 

 bottle and allowing it to run back into the bottle. Mix 

 well by shaking. Then place the milk to be tested 

 in the test-cup, setting it in a level position and allow- 

 ing the milk to run out at the bottom. Taking the bot- 

 tle of diluted rennet in one hand and the spatula in 

 the other, watch the level of the milk in the cup. The 

 moment the upper surface of the milk drops to the 

 zero mark, pour the diluted rennet into the milk and 

 stir well. Then leave it alone. When the milk coagu- 

 lates, it stops running through the glass tube. From 

 the graduated scale, read the number of spaces un- 

 covered on the inside of the cup, showing how many 

 divisions of milk have run out. The more slowly the 

 milk coagulates, the larger the amount that runs out; 

 the more quickly the milk coagulates, the smaller the 

 amount that runs out and the fewer spaces there are 

 uncovered. When about 2^2 spaces are uncovered, 

 the milk is ready for addition of rennet. The tempera- 

 ture must be watched, being tested at the start and 

 finish, especially in a cold room. 



Some objectionable features of the Marschall test 

 should be noticed. A difference in the size of the bore 

 of the glass tube in the bottom of the cup obviously 

 makes a difference in the results. It is found that the 

 size of the bore of the glass tubing varies in different 

 cups. Therefore, the results given by one cup can not 

 be compared with those of another, unless they are 

 tested on the same milk and found to agree. Special 



