Stephen Moulton Babcock (1843-1931) was an American agricultural chemist. He perfected the Babcock test for determining the butterfat content of milk, a great stimulus to the growth of the dairy industry.

Stephen Babcock was born on Oct. 23, 1843, in Bridgewater, N.Y., of Puritan stock. After graduating from Tufts University in 1866, he attended Cornell, where he was also a chemistry instructor; he obtained his doctorate in Germany at Göttingen in 1879.

Babcock invented an early method of simple milk analysis while working at the Geneva, N.Y., agricultural experimental station in 1881. He was professor of agricultural chemistry at the University of Wisconsin from 1887 to 1913 (emeritus thereafter), where most of his discoveries were made. He helped direct the Wisconsin state experimental station from 1901 to 1913.

Babcock's central interest was the chemical analysis of milk; but in 1890 he succumbed to pressure from the dairy industry and his Wisconsin colleagues to take an interest in practical, commercial matters. After studying the previous work on butterfat testing, he favored using a chemical agent to liberate the fat globules from the casein content of milk, followed by centrifugal action to complete the milk separation; he settled on sulfuric acid as the agent. The Babcock test, which he developed in 1890, was a total success; simple and reliable, it not only tested milk quality but also made it possible to evaluate cattle, fix standards for municipal milk inspection, and set fair milk prices according to quality grading, which discouraged further watering or skimming of milk by farmers. Despite opposition the test was widely accepted by 1892. Babcock improved it over the years, refining the test as late as 1910. In view of the vast increase in milk output in the United States (ninefold growth between 1870 and 1900), Babcock's test was equaled as a technical advance in dairying only by the centrifugal cream separator. He refused a patent on the test, although it saved millions of dollars for American dairymen by providing data to improve stockbreeding and by cutting butterfat loss in cream separation. The Capper Award in 1930, worth $5,000, was the sole direct monetary gain he received for his discovery.

Babcock worked from 1896 on the biochemistry of casein and its influence on cheese making. In 1897 the enzyme galactase was isolated, to which the decomposition of protein in curd was traced. In 1900 the coordinate influence of another enzyme, pepsin, was discovered and in 1903 a cold-curing process for cheese perfected. Babcock also helped prepare the way for recognition of vitamin A by studying "hidden hunger" in animals.

A few months before his death, on July 2, 1931, the New York Legislature honored Babcock with a bill to preserve his birthplace, the farm at Babcock Hill, Bridgewater.

Further Reading

• Babcock's personal papers are in the Wisconsin State Historical Society archives. The book that best describes Babcock's place in the history of the American dairy industry is Eric Lampard, The Rise of the Dairy Industry in Wisconsin (1963). See also T. Pirtle, History of the Dairy Industry (1926), and John J. Dillon, Seven Decades of Milk (1941).