MILK 



69 



results with cream. With separated milk, Lindstrom's butyr- 

 ometer gives altogether unreliable figures on account of the 

 small quantity of fat which is got. 



The test-bottles are cleaned 

 in the same manner as in the 

 Babcock test. Lindstrom's 

 butyrometer method is used 

 almost without exception in 

 Sweden, Norway, and Finland 

 for a practical determination 

 of the amount of fat in milk. 

 The accuracy is about the same 

 as with the Babcock or Gerber 

 methods, and the results with 

 whole milk generally agree to 

 within O'l per cent, of those 

 found by gravimetric analysis. 



4. Gerber s Method. 



In 1892 1 Dr. N. Gerber, of 

 Zurich, published details of 

 the method which he had 

 worked out for the determina- 

 tion of fat. This method, 

 however, only assumed its pre- 

 sent form in 1895, and at the 

 same time it was expanded 

 into a " universal method for 

 the estimation of fat," to serve 

 for the analysis of milk and 

 other dairy products. To dis- 

 solve the casein Gerber also 

 uses concentrated sulphuric 

 acid, but the method differs 

 from others in the addition of 

 amyl alcohol, which Leffmann 

 and Beam 2 had shown to facilitate the separation of the fat 

 in a pure, clear condition. 



1 Milch-Zeihuxj, 1892, p. 891 ; 1893, pp. 363 and 656; 1895, p. 169. 

 " Analytt, Vol. XVII, 1892, p. 83. 



FIG. 31. Gerber' s Test-Bottles or 

 Acido-Butyrometers. 



