RESEARCHES ON INSULIN

In the early autumn of 1924 we were invited by Professor A. A. Noyes, director of the Gates Chemical Laboratory of the California Institute of Technology, Pasadena, California, to investigate the chemical and other properties of insulin in his laboratory under a grant from the Carnegie Foundation. Commercial insulin as prepared by the Lilly Research Laboratories of Eli Lilly and Company, Indianapolis, Indiana, has served as the material for our investigation. Two forms of commercial insulin have been used by us; one a dry powder evaluated at approximately 8 rabbit units per milligram; the second a highly concentrated aqueous solution (2.44 per cent. solids) containing approximately 300 rabbit units per cubic centimeter, and with 120 milligrams of hydrochloric acid per 100 cubic centimeters.