On This Day in Science History - September 1

September 1^st is Karl Auer von Welsbach's birthday. Welsbach was the Austrian chemist who managed to isolate the elements praseodymium and neodymium from didymium.

Didymium (symbol Di) was discovered in 1841 from the mineral cerite by Carl Mosander, who believed he had discovered a new element. In 1874, Swedish chemist Per Teodor Cleve determined it was not a single element, but made up of two other components but did not manage to separate them from each other. Welsbach discovered a method of fractional crystallization that managed to separate didymium into two different colored salts. He named the green salt praseodidymium (meaning green didymium) and the pink salt neodidymium (meaning new didymium). The names were ultimately shortened by the extra 'di' to their present praseodymium and neodymium.

The name didymium is still applied to the original combination of elements and used primarily as an optical coating on lenses. Didymium filters are used in glassblowing safety glasses because they reduce the harsh yellow light from propane fires and filter out the ultraviolet light from the molten glass. These filters are also used in color photography to lower the yellow and orange light levels and make the other colors more vibrant.

Find out what else occurred on this day in science history.