|Born||21 February 1865|
|Died||11 July 1930(aged 65)|
After graduating from the University of Tokyo, he studied under William Ramsay in London, where he worked on the analysis of the rare mineral thorianite. He extracted and isolated a small amount of an apparently unknown substance from the mineral, which he announced as the discovery of element 43, naming the newly discovered element nipponium. He published his results in 1909 and a notice was also published in the Journal of the American Chemical Society. For this work, he was awarded a doctorate and the highest prize of the Tokyo Chemical Society. However, no other researchers were able to replicate his discovery, and the announcement was forgotten.
Recent research has indicated that whilst he did not identify element 43 (finally isolated in 1937 by an Italian group), he had apparently isolated element 75, rhenium, which was not otherwise successfully identified until 1925. Ogawa served as president of Tohoku University between 1919 and 1928.
- 幻の元素「ニッポニウム」を発見 小川正孝|日本の世界一
- Howe, J. S. (1909). "Recent Work in Inorganic Chemistry". Journal of the American Chemical Society. 31 (12): 1284–1305. doi:10.1021/ja01942a006.
- Kaji, M. "A discovery which served as a foothold". St. Petersburg: Through Centuries. Retrieved 2016-03-11.
- Yoshihara, H. K. (2004). "Discovery of a new element 'nipponium': re-evaluation of pioneering works of Masataka Ogawa and his son Eijiro Ogawa". Spectrochimica Acta Part B. 59 (8): 1305–1310. Bibcode:2004AcSpe..59.1305Y. doi:10.1016/j.sab.2003.12.027.
- Tohoku University page