106 



A JVrzi' Dairy Industry. 



acid is heavier than the milk and sinks directly to the 

 bottom, forming a clear layer. The acid and milk 

 should be thoroughly mixed together by shaking at 

 first with a rotary motion until the curd which forms 

 is entirely dissolved, and then completed with a 

 vigorous shake sideways. A large amount of heat is 

 evolved by the chemical action, and the liquid changes 

 gradually to a dark brown. 



WHIRLING THE BOTTLES. 



The test bottles containing the 

 mixture of milk and acid should 

 be placed in the machine directly 

 after the acid is added. An even 

 number of bottles should be 

 whirled at the same time, and 

 they should be placed in the 

 wheel in pairs opposite to each 

 other, so that the equilibrium of 

 the apparatus will not be dis- 

 turbed. When all the test bot- 

 tles are placed in the apparatus, 

 ' the coyer is placed upon the 

 jacket, and the machine turned at the proper speed 

 for about five minutes. The test should never be 

 made without the cover being placed upon the jacket, 

 as this not only prevents the cooling of the bottles 

 when they are whirled, but, in case of the breakage of 

 bottles, may protect the face and eyes of the operator 

 from injury by pieces of glass or hot acid. 



Fig.11— IMPROVED ACID BURETTE. 



