TESTING OF MILK AND CREAM 99 



put on too much suction and draw up a mouthful 

 before being thoroughly aware of amount drawn up. 

 This is a highly dangerous practice drawing up acid 

 by the pipette, therefore see that there is a 17-5 c.c. 

 acid measure with the outfit you buy. Having 

 measured our acid, it may now be added to the 

 milk in test bottle, putting it in slowly by running 

 it down the sides of the neck of the bottle. This 

 may be accomplished by holding the milk-test bottle 

 in a position so that the neck of bottle leans at an 

 angle towards the sulphuric acid which is being put 

 in. The reason is to let the acid in slowly, to 

 prevent charring or burning and so spoiling the 

 test, and also to wash down any milk or cream 

 clinging in the neck of test bottle. The bottle is 

 next shaken gently, holding it by the neck, shaking 

 slowly to and fro until the contents are darkened, 

 which is caused by the hot acid dissolving every- 

 thing in the milk except the fat. The test bottles 

 with their contents are now placed in the machine, 

 which is whirled rapidly by turning the handle for 

 about five minutes, all the fat coming to the surface 

 of the mixture in the bottle through centrifugal 

 action. The bottle is now filled up with very hot 

 clean water in order to raise the fat into the divisions 

 marked on the neck of bottle. Whirl the bottles 

 again in the machine for another two minutes, when 

 the amount of fat may easily be read off, measuring 

 it by means of a pair of compasses or dividers. 

 Each division on the scale of the milk bottle is 



