He was educated at Utrecht and The Hague High School and King"s College, Cambridge.
His main work focused on the study of alkaloids and investigations of simple nitrogenous compounds of biological importance. Barger identified tyramine as one of the compounds responsible for the biological activity of ergot extracts. He also made significant contributions to the synthesis of thyroxine. and vitamin B1
In 1936 and 1937 he worked with Joseph John Blackie searching for materials for research.
He died at Aeschi, Switzerland.
Regius professor of chemistry, University of Glasgow, 1937–1939
Professor of chemistry in relation to medicine, University of Edinburgh, 1919–1937
Professor of chemistry, Royal Holloway College, University of London, 1913–1914
Head of Chemical Department, Goldsmiths" College, 1909–1913
Fellow of King"s College, Cambridge, 1903–1909.
Royal Society; German Academy of Sciences Leopoldina.