By the time Stephen Moulton Babcock arrived at the University of Wisconsin to teach chemistry in 1887, the dairy industry in America was in turmoil. Lacking an effective test to determine the fat content of milk, creameries were buying milk by the pound, paying the same price for a skimmed or watered product as for whole milk. Consumers never could tell the quality of the dairy products they bought. “The creamery business all over the country is going to pot,” complained the university’s dean to his new chemist. “The honest men . . . aren’t taking their milk to the creameries any more.” Two years later, on May 15, 1890, Babcock announced his discovery of the butterfat test that bears his name.

Babcock had trained in agricultural chemistry in Germany and had already been working on several milk-fat tests when he came to Wisconsin. Spurred on by the sense of urgency present in the center of America’s dairyland, Babcock devised a system that liberated fat globules by dissolving the milk’s casein in sulfuric acid and running the milk through a centrifuge. The new test made it easy for dairies to measure the purity of milk and improved the quality of cheese and butter. Though his test was invaluable to the dairy industry, Babcock refused to patent it, insisting that it be “given to the public.” According to William D. Hoard, the former governor of Wisconsin, “the Babcock Test has made more dairymen honest than the Bible has ever made.”