 His early work isolating and synthesizing derivatives of glucoronic acid led to the identification of one of the specific polysaccharides in the capsule of type III pneumococci.Hotchkiss spent the 1937-1938 academic year in the lab of Heinz Holter and Kaj Linderstrøm-Lang at Carlsberg Laboratory learning protein analysis techniques.In 1938, he began collaborating with René Dubos to isolate and study antibiotics produced by soil bacteria.