TESTING BUTTER AND CHEESE FOR FAT 



103 



until the test sample weighs 9 grams. The bottle is 

 then placed in hot water until the butter melts and runs 

 into the body of the test-bottle. The fat adhering to 

 the inside walls of the funnel is washed down into the 

 bottle with 8.8 cc. (one-half pipetteful) of hot water, 

 and the same amount (8.8 cc.) of sul- 

 phuric acid is added. After the contents 

 are thoroughly mixed, the bottle is 

 placed in a centrifuge and whirled for 

 about 5 minutes. To read the result, 

 the funnel-shaped tube is rilled with hot 

 water, which raises the fat-column into 

 the graduated neck. By gently pressing 

 down or gently drawing up the rubber 

 cork at the top of the graduated neck, 

 the fat-column may be moved down or 

 up in the graduated neck so as to bring 

 the lower end of the column level with 

 the zero mark, which is indicated by a 

 ring below the bulb. The percentage of 

 fat is read directly. Before making the 

 final reading, let the bottle stand for 10 

 minutes in water at 120 F. With care- 



FIG. 35 

 BOTTLE FOR USE 



IN TESTING 



BUTTER ful attention to all details, results of 

 approximate accuracy can be obtained. 



SHAW TEST FOR FAT IN BUTTER 



This method was devised by R. H. Shaw, chemist 

 in the Dairy Division of the Bureau of Animal Indus- 

 try, U. S. Department of Agriculture (Circular 202). 

 It is a strictly gravimetric method, not only the sam- 

 ple of butter being weighed but also the amount of 



