Babcock, Stephen Moulton, 1843-1931, American agricultural chemist, b. Bridgewater, N.Y., grad. Tufts College (B.A., 1866), Univ. of Göttingen, Germany (Ph.D., 1879). He was, from 1887 to 1913, professor of agricultural chemistry at the Univ. of Wisconsin and chief chemist of the Wisconsin Agricultural Experiment Station. He is known chiefly for the Babcock test (perfected in 1890) for determining the percentage of butterfat in milk. The test advanced the modern dairy industry since it permits the rapid and accurate grading of milk at markets, discourages adulteration and thinning practices, and, by making practical the testing of the milk of individual cows, promotes the development of better dairy strains. His experimental studies in the food requirements of animals paved the way for the work of the American chemist E. V. McCollum on vitamin A. He invented an apparatus to determine the viscosity of liquids. The last two decades of his life were spent in basic research on the nature of matter and its relation to energy.