ON MILK AND MILK-TESTING 95 



Describe and give directions for using Gray's 

 moisture test. 



This test consists of a scale, glass flask, gradu- 

 ated glass tube, condenser, amyl reagent, and an 

 alcohol lamp. 



A representative lo-gram sample of butter is 

 placed in the glass flask. To this 6 c. c. of amyl re- 

 agent is added and the different parts of the test 

 then connected for use. The condenser is filled 

 with cold water. The butter and amyl mixture is 

 heated over a flame, the moisture is driven off and 

 collects in the graduated glass tube, where it can be 

 read in the form of percentage. The heating is 

 stopped as soon as the mixture in the flask becomes 

 brown and the crackling noise ceases. This usually 

 requires about six minutes. 



Should heat be applied too severely to the flask 

 the steam may go above the 15 per cent mark. 

 This should be prevented by withdrawing the heat 

 for a short time. Great care must be exercised in 

 collecting all the moisture in the graduated tube if 

 reliable readings are to be secured. 



Describe and f^ive directions for using Farrington*s 

 moisture test. 

 In Farrington's test 10 grams of a representative 

 sample of butter is placed in a small dish. The 

 dish is then placed in a special oven heated to from 

 240° F. to 270° F. under steam pressure. Here the 

 butter is left until all moisture has been evaporated, 

 indicated by the browning of the casein in sample. 

 This usually takes about 30 minutes. After the 

 moisture has been evaporated the dish and its con- 

 tents is reweighed and the difference from the 



