Introduction. 



are in use at the present time, viz.: Gerber 's acid- 

 butyrometer, the sin-acid (or no-acid) test, the lactocrite, 

 De Laval's lutyrometer, and Fjord's centrifugal cream 

 test. 1 



Of these tests the last 

 one has never, to our 

 knowledge, been intro- 

 duced into this country, 

 and the first four only to 

 a limited extent. 



11. The Gerber method 



(fig. 1) is essentially the old 

 Beimling method (7), worked 

 out independently by the 

 Swiss chemist, Dr. N. Gerber. 

 In this test sulfuric acid of 

 the same strength as in the 



Babcock test is used, and a 



FIG. 1. The Gerber acid- 

 small quantity of amyl alco- butyrometer. 



hoi is added. The amyl alcohol facilitates the separation of the 

 fat, but may introduce a source of error on account of impuri- 

 ties contained therein, when the results obtained with a new lot of 

 alcohol can not be checked against gravimetric analysis or against 

 tests made with amyl alcohol known to give correct results. This 

 method is, however, extensively used in European countries, hav- 

 ing there practically replaced the Babcock test or been adopted 

 in preference to it. 



lla. The sin-acid test was invented by the German chemist 

 A. Sichler and published in 1904. 3 In place of the sulfuric acid 

 used in the Babcock and Gerber tests, Sichler employs a solution of 



J The Lister-Babcock milk test advertised in English papers and 

 known as such in England, is the regular Babcock test, to which the 

 English manufacturers have affixed their name; the same applies to the 

 Ahnorn-Babcock and the Krugmann-BdbcocTc methods. 



2 Gerber, Die praktische Milch priifung, 7th edition, 1900. 



3 Milchztg., 1904, p. 417. The word sin (sine) is Latin and means 

 without; hence, when introduced into this country in 1909 the method 

 was called the no-acid test. 



