104 GRADING AND TESTING MILK AND CREAM 



the sample before centrifuging it. This was a pioneer test but is 

 not now in use. 



(2) The Babcock test, invented by Dr. Babcock of the Wis- 

 consin Experiment Station and published in July, 1890. This 

 test is so widely and favorably known and is in such general 

 use, especially in America, that it seems unnecessary to do more 

 than refer to it. It is simple, speedy and accurate, and the cost 

 of a test is small, a single, cheap chemical, commercial sulphuric 

 acid, being used. 



(3) The Gerber test, brought out in 1892. In this test two 

 chemicals are used, viz., commercial sulphuric acid and amyl 

 alcohol. It is used quite extensively in Europe. 



(4) The Sinacid Butyrometer. This test was devised by 

 Sichler of Germany in 1904. No acid is used in the test, hence 

 the name " Sinacid." The chemicals used are sodium hydrox- 

 ide, Rochelle salt and iso-butyl alcohol. It is necessary to heat 

 the samples by placing them in hot water before centrifuging 

 them. 



All of these tests were designed primarily for the testing of 

 milk and such milk products as cream, and for this purpose 

 they are reliable; but in testing the by-products of the dairy, 

 skim-milk and buttermilk, they all give results that fall con- 

 siderably below those obtained by chemical analysis (the Rose- 

 Gottlieb test). No doubt this is the main reason for the failure 

 there has been to make a thorough study of the losses of fat in 

 buttermilk and how to overcome them. Hence, when the 

 American Association of Creamery Butter Manufacturers began 

 its study of losses of fat in buttermilk it was confronted with 

 the problem of devising a suitable test for the accurate deter- 

 mination of the per cent of fat in buttermilk, 



Trials were made of different combinations of chemicals, 

 such as, sulphuric acid and amyl alcohol, sulphuric acid and iso- 

 butyl alcohol, and sulphuric acid and normal butyl (w-butyl) 

 alcohol. After extensive experiments had been made sulphuric 

 acid and n-buty\ alcohol were selected as the most suitable 

 combination to use, and for the following reasons: 



(i) The results, with duplicate tests, are exceptionally uni- 



