William Crookes (London, 1832 - 1919), English physicist and chemist. He discovered the chemical element thallium and was a tireless and imaginative inventor. His cathode ray discharge tube was part of all experimental laboratories and made it possible to discover the electron and the photoelectric effect.
William Crookes was the eldest of seventeen children of a London tailor. He studied in his youth at the Royal College of Chemistry. His first job was as Hofmann's assistant. In 1854 he entered the Oxford Observatory as an assistant, and a year later he gained the chair of chemistry at the University of Chester. After teaching, a substantial inheritance from him enabled him to open his own research laboratory in London and edit the influential Chemical News between 1859 and 1906.
In 1861, examining the emission spectrum of a piece of crude selenium, he observed a new, bright line, which led him to isolate a new chemical element, thallium (number 81 on the periodic table of the elements), and to examine its properties. chemical properties. To this end, he built the radiometer that bears his name, a modification of the Hittorf radiometer, which consists of blades with four very light fins, with their sides black, inserted in a glass ampoule with a low-pressure gas inside. inside. In the presence of radiant energy, the blades move. This apparatus confirmed the kinetic theory of gases. He came to affirm in 1879 the existence of a new state of matter, which he called radiant matter, which earned him a prize from the French Academy of Sciences endowed with a commemorative medal and the sum of 3,000 francs. This prize allowed him to become an Academician of the Institute of Sciences of France.
Crookes also studied electrical discharges in a vacuum tube, discovering that cathode rays traveled in straight lines, cast shadows, heated objects in their path, and were deflected by magnetic fields. From all this he concluded that they were particles of negative electrical charge. Twenty years later, J. J. Thomson succeeded in identifying them as electrons.
Crookes' scientific concerns led him to invent a multitude of objects, from chemical dyes for the textile industry to antiseptics. He invented the spintariscope, with which the emission of alpha particles from radioactive elements was detected. He investigated industrial diamond sourcing, studied sugar beet sourcing, and built sanitation.
He collected in a treatise the need to obtain chemical fertilizers from the nitrogen in the air in order to ensure the maintenance of crops and even developed a theory about telepathy in which it was stated that a wave communication was established between the brains. Crookes more than made up for his ignorance of theoretical matters (particularly mathematics) with an unusual flair for experimentation. His many works include Disinfectants for Cattle plague (1866), Manufacture of Beetrot sugar in England (1870), Dyeing and Tissue printing (1882), London Water (1896), and Diamonds (1909).
