Professor William Crookes, c mid-20th century

William Crookes, born 17 June 1832, died 4 April 1919. Crookes was an English chemist and physicist who worked on spectroscopy. He pioneered vacuum tubes and invented the Crookes tube in 1875. This discovery changed the face of chemistry and physics. He is credited with discovering the element thallium in 1861. He invented the Crookes radiometer. At age 16, he attended the Royal College of Chemistry, now presently part of Imperial College London. He worked for the Royal College of Chemistry between 1849-1854, Radcliffe Observatory (1854-1855), and Chester Diocesan Training College (1855-1856). He married Ellen Humphrey in 1856, forcing him to resign from his post at Chester as he was no longer a bachelor. Crookes had six sons and three daughters. Crookes then became an independent working in photographic chemistry. He was one of the first scientists to investigate plasma and identified it as the fourth state of matter, as a result of the construction of his vacuum tubes. In 1886, he was elected as a member to the American Philosophical Society. He died in 1919, aged 86. He was much awarded in his life, winning the Royal Medal in 1875, the Albert Medal in 1899, and the Copley Medal in 1904. He was given the Order of Merit in 1910. He was the 41st President of the Royal Society between 1913-1915. He was also 6th President of the Society for Psychical Research between 1896-1899.