A DESCRIPTION OF COCHRAN'S METHOD 



FOR THE DETERMINATION 



OF FAT IN MILK. 



FOR THE USE OF DAIRYMEN. 



OEVERAL, methods for the determination of fat in milk, of 

 ^ such a character that they can be carried out without special 

 acquaintance with chemical manipulation, have been described 

 recently in Experiment Station bulletins and chemical journals. 

 All of them depend upon the same general principle — a partial 

 decomposition or solution of some of the constituents of the milk 

 by heating it with acid or alkali, and in most cases taking up the 

 separated fat by ether or gasolene ; in one method, (Patrick's), no 

 ether or gasolene is used, and in so far this method has the advan- 

 tage over all others. 



These methods differ in respect to the simplicity of the special 

 apparatus required, and of the manipulation. In respect to accu- 

 racy, they are about the same as shown by the results of a num- 

 ber of comparative tests of them recently made in this laboratory, 

 and exhibited in the following table. The tests of Patrick's 

 method w r ere made by Mr. W. P. Cutter, of the Experiment Sta- 

 tion, the others by Mr. N. E. Wilson, of the University. The 

 figures show the per cent, of fat found. 



The description of the several methods can be found as follows : 



The method of F. G. Short, Annual Report, Wisconsin Experi- 

 ment Station, 1888. 



The method of C. L,. Parsons,. Journal of Analytical Chem- 

 istry, III., 273. 



The method of Professors Failyer and Willard, Journal of Ana- 

 lytical Chemistry, III., 295. 



The method of Professor G. E. Patrick, Bulletin 8, Iowa Experi- 

 ment Station, 1890. 



The method of Mr. C. B. Cochran, Journal of Analytical Chem- 

 istry, III., 381. 



