34 



Factory Cheese-making. 



sampling the milk is weig-hed, and then run from the 

 receiving-can through a tin conductor into the storage 

 vats. Each vat ordinarily holds about 500 gallons. 



The temperature of the milk is then raised. Between 

 the wooden part of the vat and the tin lining there is an 

 open space, which is filled with water; the water is heated 

 by steam introduced through perforated pipes running in 

 this space along the whole length of the vat, and thus the 

 temperature of the milk is gradually raised. The heating 

 generally begins while the vat is filling, or as soon as it 

 is filled. After the required temperature of 82"" F. to 86^ F. 

 is reached the heating is stopped. 



The next step is to ascertain if the milk is in a condition 

 xipe enough to add the rennet. The usual method of 

 determining this is by means of the rennet test, for which the 

 following specially-prepared apparatus is used, viz., an 

 enamelled cup, graduated on the inside, with a fine hole in 

 the bottom, a pipette of i cubic centimetre, and a small 

 bottle graduated on the neck. With the pipette, i cubic centi- 

 metre of rennet-extract is measured into the bottle, which is 

 then tilled with water to the mark on the neck, the pipette 

 being rinsed into the bottle. If the extract used be of 

 ^standard strength, this will give a uniform solution at all 

 times. The cup is then filled with milk, and placed on the 

 edge of the vat. When enough milk has run from the cup 

 to bring the surface of the milk down to the first mark on the 

 inside, the diluted rennet is quickly added, the whole stirred 

 w^ell, and the cup left undisturbed. As soon as coagulation 

 takes place the milk stops running through the fine hole in 

 the bottom of the cup. The graduation on the inside of the 

 cup shows the amount of milk which has run out, and from 

 this the degree of ripeness to which the milk has attained is 

 judged. The temperature of the milk and the strength of the 

 rennet being always uniform, the variation in the amount of 

 milk running from the cup before coagulation takes place 

 depends solely upon the degree of acidity of the milk. 



When the milk is very sweet the ripening process is hastened 

 by using a small quantity of clean sour milk, free from, any 

 taint. If this sour milk is thick, it is strained through a 



