Dr. Carl Auer von Welsbach
Discoverer of four elements
In Heidelberg, at the Institute of Physical Chemistry, which was headed by Robert Wilhelm Bunsen, Auer acquired all the skills and knowledge needed later for his discoveries. Among other things, he got to know and apply the spectral analysis developed by Bunsen and Kirchhoff, which was one of the key techniques for his chemical discoveries. During his studies in Heidelberg, he became acquainted with the Rare Earths, a group of elements that was still economically insignificant at the time. This determined later his scientific and, to a large extent, his economic success. From then on, Auer worked intensively on the basis of the experience gained at Bunsen with the optimization of the chemical separation methods for the extremely hard to isolate rare earth elements.
In 1839 Mosander discovered among other things the Didymia (twin brother of Lanthana). But it was observed even then that the atomic weight of the Didym was slightly different depending on the source of raw materials (ore deposits) and could possibly consist of even more difficult to isolate different elements. The ore deposit dependence of the atomic weight and the results of spectral analytical investigations induced Auer von Welsbach to solve the puzzle with the techniques learned at Bunsen. This was done with an enormous expenditure of time and purely private means, only to satisfy the scientific desire of the knowledge gain.
After enormous effort, thousands of crystallization steps (dissolve, crystallize, separate, quality control with spectrometer and again from the front) had Auer from the Didym (Greek Gemini) finally isolated two salts. One was amethyst-colored and this he called "Neo-Didymium" (Greek "New Twin"). The other green-colored salt he called "Praseo-Didymium" (Greek "Leek Green Twin"). The names were later shortened to neodymium and praseodymium.
By this achievement, Auer von Welsbach was admitted in 1885 at the age of 27 into the rank of those scholars who may claim the dignified honor to be discoverers of new elements and has thus set himself a memorial.
Auer also observed similar phenomena in the Ytterbium and with the same, now greatly improved technology, he discovered in 1907 that the element Ytterbium to date was also a mixture of two elements and he called them Aldebaranium (= Ytterbium) and Cassiopeium (= Lutetium). In the same year, the French chemist Georges Urbain disassembled the "Ytterbium Earth" and named the two elements Neo-Ytterbium (= Ytterbium) and Lutetium (old name for Paris). From this emerged the longest lasting dispute of the discoverer priority in the history of chemistry. Finally, in 1923, the German Atomic Weight Commission recognized Auer's claim. Nevertheless, Auer's Cassiopeium is internationally called Lutetium and in recent literature are called discoverer G. Urbain, C. Auer and C. James.