Dense, reflective precious metal m.p. 3180 ºC; 5756 ºF b.p., estimated 5627 ºC; 10,161 ºF density 21.02 g/cc; 1312.24 pound/cubic foot	memory peg
	1925 (1908) Walter & Ida Noddack & Otto Berg, Germany (earlier in 1908 by Masataka Ogawa, Japan)
	Rheinland (Rhineland), region in Germany

Element #75 was isolated in 1908 by the Japanese chemist Masataka Ogawa and named Nipponium. He inadequately assigned it as element #43 (Technetium). From the modern chemical viewpoint it has to be considered to be element 75. (note).

In 1925 the discovery of elements #43 (Medeleyev's Eka-Manganese) and #75 (Dvi-Manganese), the last missing elements on the main periodic table, was announced by Walter Noddack (1893-1960), Ida Eva Tacke (1896-1978, she married in 1926 Walter Noddack) and Otto Berg (1873-).

Platinum ores were known to contain elements #24-29, 44-47, and 76-79, while rare-earth minerals (columbite, gadolinite) contain elements #39-42 and 72-74. Noddack and Tacke at the Physico-Technical Testing Office in Berlin started in 1922 with their attempts to separate elements #43 and #75, first from Platinum ore, but since that was too costly, soon continued with the rare-earth minerals. The X-ray specialist Otto Berg at Werner-Siemens Laboratory did the identification. The team found weak X-ray spectral lines when electrons excited the elements. After three years research, element #75 was separated from gadolinite and named Rhenium (Latin for the River Rhine), after the Rheinland (Rhineland), the homeland of Ida Tacke (she was born in Lackhausen/Wesel).

Shortly afterwards they separated element #43 and named it Masurium after Noddack's homeland, the Masurian province. Therefore, some historians of chemistry consider that both names contain a large dosis of nationalism: the Rhine region and the Masurian swamps were during the First World War the most succesfull battle places for the German troops. Their discovery of Masurium was not confirmed (see Technetium). By working up 660 kg of molybdenite they were able in 1928 to extract 1 g of Rhenium.

About the same time, element #75 was also discovered, independently by the British investigators F.H. Loring and J.F.G. Druce in manganese sulphate, and by the Czechs Jaroslav Heyrovský (1890-1967) and V. Dolejsek. I found no further information on these claims.

Further reading:

• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 823-827.