Johann Wilhelm Hittorf

Who was Johann Wilhelm Hittorf?

Johann Wilhelm Hittorf was a German physicist who was born in Bonn and died in Münster, Germany.

Hittorf was the first to compute the electricity-carrying capacity of charged atoms and molecules, an important factor in understanding electrochemical reactions. He formulated ion transport numbers and the first method for their measurements.

He observed tubes with energy rays extending from a negative electrode. These rays produced a fluorescence when they hit the glass walls of the tubes. In 1876 the effect was named "cathode rays" by Eugen Goldstein.

Hittorf's early investigations were on the allotropes of phosphorus and selenium. Between 1853 and 1859 his most important work was on ion movement caused by electric current. In 1853 Hittorf pointed out that some ions traveled more rapidly than others. This observation led to the concept of transport number, the fraction of the electric current carried by each ionic species. He measured the changes in the concentration of electrolyzed solutions, computed from these the transport numbers of many ions, and, in 1869, published his laws governing the migration of ions.