The ignored discovery of the element Z = 43

Until now Perrier and Segrè (Palermo, 1937) are credited for the first observation of the element Z = 43, called technetium (Tc). We give arguments for the statement that Walter Noddack, Ida Tacke and Otto Berg (Berlin, 1925) should be credited for the discovery of this element. In their search for the missing eka-manganese elements with Z = 43 and Z = 75 they observed the X-rays of these elements, with the peculiar behaviour though that the Z = 43 lines only appeared in ores, quoted to contain percentage quantities of uranium. The presence of element Z = 43 in uraniumcontaining ores can now be explained through the long-living fission product ⁹⁹43 in their samples; they proposed the names masurium (Ma) and rhenium (Re) for the discovered elements. By reanalysing the original experimental conditions, we conclude that the detection limit for their observing the X-rays of Z = 43 can be 1000 times lower than the 10^-9 detection limit for the element Z = 75. This brings us very close to the expected abundance of Z = 43 in the analysed samples, such that we do not see reasons for questioning the credibility of the experimental evidence.