Ralph Edward Oesper (14 June 1886 – 10 December 1977) was an American chemist and historian of chemistry. He is noted for his biographies of scientists, emphasizing their personal lives in addition to their scientific contributions. Oesper translated significant works in the field of chemistry to various languages especially English. As an independent investigator, he developed improved analytical methods. These contributions included new reagents for certain types of titrations. One such new reagent, Oesper's Salt, is named for him. Personal life and education Oesper was born in Cincinnati and attended public schools before enrolling at the University of Cincinnati in 1904. There he earned a bachelor's degree in 1908, a master's degree in 1909, and a PhD in 1914 with Lauder William Jones as his thesis advisor. These degrees were all in the field of chemistry or analytical chemistry. On 29 June 1910 he married Helen Gertrude Wilson (1885–1972). The couple had one child, Peter Oesper, who also became a chemistry professor. Career Following completion of his PhD degree, Oesper taught for a brief time at New York University and then at Smith College as a non-tenure track faculty member. He then in 1918 became a tenure track faculty member and later a full professor at the University of Cincinnati, where he remained until his retirement in 1951 as professor emeritus. In retirement, he remained active as an occasional lecturer, a journal editor, and a translator of scientific books and articles. Oesper wrote approximately 300 scientific articles on analytical and organic chemistry, colloid chemistry and chemical history. He was fluent in the German language and translated about 20 chemistry books and numerous articles from German into English. He also translated chemistry articles from French and Dutch into English. Analytical chemistry Early in his career as an independent researcher, Oesper continued investigations in analytical chemistry. His scientific accomplishments at this stage of his career included demonstrating the utility of the compound ferrous ethylene diamine sulfate in certain applications especially redox titrations. This compound replaced Mohr's salt (ferrous ammonium sulfate) in many applications because of its greater stability compared to Mohr's salt. He published these findings in 1947. Ferrous ethylene diamine sulfate is often referred to as "Oesper's Salt", in recognition of Oesper's scientific contributions. A further contribution to analytical chemistry was his demonstration of the use of naphthidine as an indicator for certain chromate titrations such as for chloride ion. This