William Crookes

Sir William Crookes, OM , FRS (June 17 1832 – April 4 1919) was an English chemist and physicist.

Related Topics:
OM - FRS - June 17 - 1832 - April 4 - 1919 - English - Chemist - Physicist

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Sir William attended Royal College of Chemistry in London. Working on spectroscopy, in 1861 he discovered a previously unknown element with a bright green emission line in its spectrum. He named the element thallium, from the Greek thallos, a green shoot. Crookes also identified the first known sample of helium, in 1895.

Related Topics:
Royal College of Chemistry - Spectroscopy - 1861 - Thallium - Helium - 1895

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He was the inventor of the Crookes radiometer, which today is made and sold as a novelty item. He also developed the Crookes tubes, investigating canal rays.

Related Topics:
Crookes radiometer - Crookes tube - Canal ray

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In his investigations of the conduction of electricity in low pressure gases, he discovered as the pressure was lowered, that the negative electrode appeared to emit rays (the so-called cathode rays, now known to be a stream of free electrons, and used in cathode ray display devices). He was one of the first scientists to investigate what are now called plasmas.

Related Topics:
Electricity - Cathode ray - Stream - Free electron - Plasma

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