Hittorf, Johann Wilhelm (1824–1914)

German physicist. In 1862 Hittorf and Julius Plücker discovered the influence of temperature on the spectra of substances. In 1869 Hittorf performed experiments in relation to the passage of electricity through rarefied gases noticing the deflective influence exercised by a magnet on the rays proceeding from the cathode. He also investigated allotropic forms of selenium and phosphorus producing black crystals of the latter.

Hittorf was born in Bonn, Germany. At Munster University he was professor of physics and chemistry (1852–79) and director of physical laboratories (1879–89). Hittorf's work with electricity led to later research by the English scientist William Crookes and the identification of cathode rays as electrons by English physicist J J Thomson.