Chemistry by the History division of the American Chemical Society. As a chemical historian, he was primarily concerned with the history of physical and inorganic chemistry at the end of the 19th and beginning of the 20th centuries, as well as the history of chemical apparatus. He endeavoured to bring the history of chemistry closer to more chemistry students, detached from the history of science.

Jensen was an article contributor to Encyclopedia Britannica. He was also a caricaturist