Babcock is best known for his test for butterfat in milk, introduced in 1890. By using sulfuric acid to release the fat from its normal suspension and centrifuging and diluting, it was possible to measure directly the percentage of fat by observing it in the neck of a specially designed test bottle. The simplicity of the test permitted its use by persons without scientific training. Its use altered the economics of dairying and stimulated growth of the dairy industry.
After the development of the test, it was much easier for dairy operations to not only compensate farmers fairly, but to produce a consistent product that consumers could depend on. The Babcock test was also utilized by farmers to selectively breed for cows who produced milk with higher butterfat content—the tests were usually done monthly by an employee of the local Dairy Herd Improvement Association (DHIA).
In 1911, the American Dairy Science Association’s Committee on Official Methods of Testing Milk and Cream for Butterfat, chaired by O. F. Hunziker, met in Washington DC with the U.S. Bureau of Dairying, the U.S. Bureau of Standards and manufacturers of glassware. Standard specifications for Babcock glassware were published as a result of this meeting.