Babcock Test. 47 
Agricultural Experiment Station, and published in 
Bulletin No. 8, February, 1890, of the Iowa Experi- 
ment Station. In this test the solids of the milk 
were destroyed by a mixture of acetic, sulphuric and 
hydrochloric acids, and the fat brought to the sur- 
face by boiling. The test was made in a flask with 
a narrow graduated neck. A measured quantity of 
milk was put in the flask, a sufficient amount of 
the acids added, and the whole boiled for ten or fif- 
teen minutes. The Iowa Station test was a great 
improvement upon any that preceded it in point of 
simplicity, accuracy and length of time required. 
Cochran’s method.—This method was invented by 
C. B. Cochran, of the Pennsylvania State Board of 
Health, and published in the Journal of Analytical 
Chemistry, Vol. III., page 381. In this method 
the solids of the milk other than the fat were de- 
stroyed by the use of a mixture of acetic and sul- 
phuric acids, aided by boiling. When the milk 
solids were thus completely disintegrated, the fat was 
brought to the surface by the aid of ether, and then 
the whole mass further boiled until the ether was all 
evaporated. The clear melted fat was then meas- 
ured by transferring it to a vessel with a gradu- 
ated neck. The Cochran method was simple in 
details, but required rather delicate manipulation in 
transferring the melted fat from one vessel to an- 
other. It, however, gave very good results in a 
comparatively short time. 
The Babcock test.—This test was invented by 
Dr. S. M. Babcock, chemist of the Wisconsin Agri- 
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