William Crookes


William Crookes : biography

17 June 1832 – 4 April 1919

Crookes investigated the properties of cathode rays, showing that they travel in straight lines, cause fluorescence in objects upon which they impinge, and by their impact produce great heat. He believed that he had discovered a fourth state of matter, which he called "radiant matter",Radio-activity induced by the oscillatory discharge, or, The subsequent radio-active emanation from substances exposed to the Tesla oscillatory discharge. Harry Marshall Diemer, Ralph Stuart Cooper. Cornell University, 1903. . but his theoretical views on the nature of "radiant matter" were to be superseded.Chemist & Druggist, Volume 60. Benn Brothers., 1902. . He believed the rays to consist of streams of particles of ordinary molecular magnitude. It remained for Sir J. J. Thomson to expound on the subatomic nature of cathode rays (consisting of streams of negative electronsNegatively electrified particles whose mass is only 1/1840 that of a hydrogen atom). Nevertheless, Crookes’s experimental work in this field was the foundation of discoveries which eventually changed the whole of chemistry and physics.

Crookes’ attention had been attracted to the vacuum balance in the course of thallium research. He soon discovered the phenomenon upon which depends the action of the Crookes radiometer, in which a system of vanes, each blackened on one side and polished on the other, is set in rotation when exposed to radiant energy. Crookes did not, however, provide the true explanation of this apparent "attraction and repulsion resulting from radiation".

After 1880, he lived at 7 Kensington Park Gardens, where all his later work was carried out in his private laboratory.

Later Years

Sir Leslie Ward 1902]] Crookes identified the first known sample of helium, in 1895. Crookes was knighted in 1897.

In 1903, Crookes turned his attention to the newly discovered phenomenon of radioactivity, achieving the separation from uranium of its active transformation product, uranium-X (later established to be protactinium). He observed the gradual decay of the separated transformation product, and the simultaneous reproduction of a fresh supply in the original uranium. At about the same time as this important discovery, he observed that when "p-particles", ejected from radio-active substances, impinge upon zinc sulfide, each impact is accompanied by a minute scintillation, an observation which forms the basis of one of the most useful methods in the technique of radioactivity.

Crookes wrote a small book on diamonds in 1909. In 1910, Crookes received the Order of Merit. He died in London on 4 April 1919, two years after his wife. He is buried in London’s Brompton Cemetery.Brock (2004)


In 1870 Crookes decided that science had a duty to study preternatural phenomena associated with spiritualism (Crookes 1870). Judging from family letters, Crookes had already developed a favorable view of spiritualism by 1869.Doyle 1926: volume 1, 232 – 233 In this he was possibly influenced by the untimely death of his younger brother Philip in 1867 at age 21 from yellow fever contracted while on an expedition to lay a telegraph cable from Cuba to Florida.Crookes 1868 Nevertheless, he was determined to conduct his inquiry impartially and described the conditions he imposed on mediums as follows: "It must be at my own house, and my own selection of friends and spectators, under my own conditions, and I may do whatever I like as regards apparatus".Doyle 1926: volume 1, 177) Among the mediums he studied were Kate Fox, Florence Cook, and Daniel Dunglas HomeDoyle 1926: volume 1, 230-251) Among the phenomena he witnessed were movement of bodies at a distance, rappings, changes in the weights of bodies, levitation, appearance of luminous objects, appearance of phantom figures, appearance of writing without human agency, and circumstances which "point to the agency of an outside intelligence".

To find support and assistance for his research, he joined the Society for Psychical Research, becoming its president in the 1890s: he also joined the Theosophical Society and the Ghost Club, of which he was president from 1907 to 1912. In 1890 he was initiated into the Hermetic Order of the Golden Dawn.

His report on this research in 1874, concluded that these phenomena could not be explained as conjuring, and that further research would be useful. Crookes was not alone in his views. Fellow scientists who came to believe in spiritualism included Alfred Russel Wallace, Oliver Lodge and Lord Rayleigh.Doyle 1926: volume 1, 62) Nevertheless, most scientists were convinced that spiritualism was fraudulent, and Crookes’ final report so outraged the scientific establishment "that there was talk of depriving him of his Fellowship of the Royal Society." Crookes then became much more cautious and didn’t discuss his views publicly until 1898, when he felt his position was secure. From that time until his death in 1919, letters and interviews show that Crookes was a believer in spiritualism.Doyle 1926: volume 1, 169 – 170, 249 – 251