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Sir  William Crookes (1832–1919), by Albert Ludovici, c.1884–5Sir William Crookes (1832–1919), by Albert Ludovici, c.1884–5
Crookes, Sir William (1832–1919), chemist and science journalist, was born on 17 June 1832 at 143 Regent Street, London, the eldest son of the sixteen children of Joseph Crookes (1792–1884), a tailor from Yorkshire, and his second wife, Mary Scott of Aynhoe, Northamptonshire. (There were another five children from Joseph's first marriage.) He regarded himself as a family ‘sport’, since no other sibling showed the slightest interest in science. He was educated at Prospect House School, Weybridge, and began his scientific career at the age of sixteen when he entered the Royal College of Chemistry in Oxford Street, London, under the directorship of August Wilhelm Hofmann. By then his father, having established a successful gentlemen's outfitters in Regent Street, had moved to Hammersmith, and Crookes commuted to Oxford Street every day from there.

Scientific career, 1849–1873

From 1849 to 1854 Crookes was one of Hofmann's personal assistants, in which capacity he was able to begin an original investigation of new compounds of selenium, the selenocyanides. These formed the subject of his first publications in 1851. Hofmann's connections with the Royal Institution, however, brought Crookes to the notice of Faraday, who, with his friends Charles Wheatstone and George Stokes, turned him away from Hofmann-type organic chemistry towards chemical physics, then exemplified by the optical problems of photography and, later, spectroscopy.

Crookes left the Royal College and became in 1854 superintendent of the meteorological department of the Radcliffe (Astronomical) Observatory in Oxford, where his photographic skills were fully deployed; the following year he was appointed lecturer in chemistry at the Chester Anglican teachers' training college, and on 10 April 1856 he married Ellen, daughter of William Humphrey, of Darlington, with whom he had ten children, though only three sons and a daughter survived into adulthood. Soon afterwards the couple moved back to London, and from then on, apart from extensive European travels, his life was spent in the capital and was devoted mainly to independent research, journalism and consultancy. In 1854, with John Spiller, he had devised the first dry collodion process and for some ten years he worked enthusiastically at photography, editing journals on the subject, investigating the spectral sensitivity of the wet collodion process, and attempting to apply photography to the scientific recording of polarization, astronomical objects, and spectra.

Shortage of money as a young man does much to explain the catholicity of Crookes's interests, many of which were clearly motivated by the possibility of commercial rewards. Science and business were integrated activities throughout his life. In the world of commerce he drove many a hard bargain, but although he eventually made a comfortable living from such ventures as the sodium amalgamation method of gold extraction (which he worked in north Wales) and the chemical exploitation of sewage as a fertilizer (which he exploited at Crossness), as well as electric lighting, achieving this financial success was hard. By the early 1880s he was comfortably off, and could afford to entertain on an impressive scale. Apart from running a successful analytical consultancy from a laboratory at his home at 20 Mornington Road (where the Crookes family lived until 1880, when they moved to 7 Kensington Park Gardens, the first house in England to be lit by electricity), the foundation of his financial success came through the launch of the weekly Chemical News in 1859, and journalistic ventures with James Samuelson's Popular Science Review in 1861 and, three years later, with the Quarterly Journal of Science. Chemical News, which he edited regularly himself until 1906, was conducted on much less formal lines than other commercial journals; it eventually closed in 1932.

That Crookes took some years to abandon the idea of an academic position is clear from his abortive attempt in 1862 to obtain a chair of chemistry at the Royal Veterinary College in London. Ironically, he would have been in a better position three years later when his efforts to promote carbolic acid (phenol) as a germicide during the great cattle plague (rinderpest) of 1865–6 brought him considerable prominence in government and veterinary circles. His growing family and his increasingly complex instrumental researches in the 1870s were sustained by relentless hard work in journalistic ventures, and his success in obtaining analytical contracts as sanitary and food adulteration legislation provided increasing business. In particular, the water companies, besieged by criticisms of water quality, provided handsome retainers and regular consultancy work.

Crookes's life was one of unbroken scientific and business activity. He worked regularly in his laboratory in the mornings, and after dinner through the evening into the early hours. He was eclectic in his interests, ranging over pure and applied science, economic and practical problems, and psychic research. All of these interests collectively made him a well-known personality within the late Victorian scientific community. He received many public and academic honours. He was knighted in 1897 and in 1910 appointed to the Order of Merit. At various times he was president of the Chemical Society (1887–9), the Institution of Electrical Engineers (1890–94), the Society for Psychical Research (1897), the British Association for the Advancement of Science (1898), and the Society of Chemical Industry (1913). Each of his presidential addresses proved a tour de force, gaining him worldwide publicity. He was a Davy and Copley medallist of the Royal Society (1888, 1904), its foreign secretary (1908–13), and its president (1913 to 1915), having been elected FRS in 1863. He was also closely involved in the affairs of the Royal Institution until 1912, when a quarrel with its director, Sir James Dewar, over his son, Henry Crookes, led to his resignation.

The work of Crookes extended over the regions of both chemistry and physics. Its salient characteristic was the originality of conception of his experiments, and the skill of their execution. Frequently aided at the theoretical level by colleagues such as George Stokes, his speculations were equally imaginative and stimulating. He was an able syncretist of other scientists' hints and suggestions, and by weaving these together imaginatively he acquired a well-deserved reputation as a Victorian sage. Nevertheless, he was always more effective at experiment than in interpretation. Spectroscopy, introduced by Bunsen and Kirchhoff in 1859, was received by Crookes with great enthusiasm, and, on applying it to the examination of the seleniferous chimney deposits from a sulphuric acid factory, he discovered an unknown green line in the spectrum. The isolation of the new metallic element, thallium, followed in 1861. Through this work and the controversy with French scientists over C. A. Lamy's claim to have discovered the element at the same time, his reputation became firmly established. A decade's work produced the atomic weight of thallium which confirmed his reputation for meticulous analytical precision in 1873.

Cathode rays and lanthanides

Two lines of research then occupied Crookes's attention for many years. These were the properties of highly rarefied gases, with which he began to occupy himself immediately, and the investigation of the elements of the ‘rare earths’, upon which he embarked shortly after 1880. His attention had been attracted to the first problem in using a vacuum balance during the course of the thallium researches. Believing, erroneously, that he had uncovered a relationship between gravity and heat, he was led to the phenomenon upon which depended the action of the ‘lightmill’ or radiometer. In this popular instrument a system of vanes, each blackened on one side and polished on the other, is set in rotation on a pivot in an evacuated space when exposed to radiant energy. This apparent attraction and repulsion resulting from radiation, which Crookes initially attributed to a psychic force, was explained in terms of the kinetic theory of gases by Stokes, Maxwell, and others. His work on this phenomenon led Crookes to investigations of fundamental importance in understanding the nature of matter, for in seeking a mechanism for the rotation, he passed electrical discharges through the rarefied gases. He then quickly discovered, with the aid of his young assistant, Charles Gimingham (d. 1890), that as the attenuation of the gas was made greater the dark space around the cathode (negative electrode) extended, while rays (soon termed cathode rays) proceeded from the anode (positive electrode).

In a series of spectacular and ingenious experiments Crookes showed that these rays travelled in straight lines, cast shadows, caused phosphorescence in objects upon which they impinged, and produced heat by their impact. Following an earlier hint of Michael Faraday's, he believed that he had discovered a fourth attenuated state of matter, which he called radiant matter. It remained for J. J. Thomson in 1897 to demonstrate that the rays were not streams of particles of ordinary molecular magnitude, but subatomic particles of negative charge whose mass was only 1/1800 that of an atom of hydrogen. However, it was Crookes's success in producing a vacuum of the order of one millionth of an atmosphere that made possible the discovery of X-rays as well as of the electron; his experimental work in this field was the foundation of nuclear physics and of the electronic theory that altered the whole conception of chemistry and physics at the beginning of the twentieth century. ‘Crookes's dark space’ and the ‘Crookes tube’ have become part of the vocabulary of modern physics. It was characteristic of Crookes that, though already in his sixties, he readily and enthusiastically accepted the new interpretation of his work.

For many years Crookes conducted laborious experiments on the rare earth elements (lanthanides), elements so similar to one another in chemical properties that special methods for their separation had to be devised. Throughout this exacting work with his assistant, James H. Gardiner, he employed spectroscopic methods for following the course, and testing the completeness, of the separation of one element from another. What had been one of the most obscure regions in inorganic chemistry gradually became clear. In the course of these years Crookes was increasingly led to speculate on the existence of ‘meta-elements’, clusters of elements resembling one another so closely that in most ways the cluster behaved like a single individual or element. Further stimulated by Darwin's theory of evolution and N. J. Lockyer's speculations concerning the dissociation of the elements in the sun and stars, Crookes daringly speculated that he had found evidence of the evolution of the elements, which was the theoretical underpinning of Mendeleyev's periodic law and table.

Further experimental work and psychic research

Crookes's ‘meta-elements’ bear a superficial similarity to isotopes, a concept which arose in 1912–13 from the phenomenon of radioactivity—another field into which Crookes threw himself wholeheartedly. In 1900 he achieved the separation from uranium of its active transformation product, uranium-X. He observed the gradual decay of the separated transformation product, and the simultaneous reproduction of a fresh supply in the original uranium. His own explanation, in terms of energy gained from the atmosphere, was soon superseded by that of Rutherford's and Soddy's disintegration theory. Crookes also observed that when alpha particles, ejected from radioactive substances, impinge upon zinc sulphide, each impact is accompanied by a minute scintillation. This observation became the basis of a detection instrument (spinthariscope) that played an invaluable role in early work on radioactivity until the invention of the Geiger counter in 1908.

Crookes published numerous papers on spectroscopy, a subject which always held a great fascination for him, and he made researches on a host of minor subjects. In addition to various technical books and translations, he wrote a standard treatise, Select Methods in Chemical Analysis (1871), and a small book, Diamonds (1909), a subject to which he had devoted some study during two visits to South Africa in 1896 and 1905. He frequently served the government in an advisory capacity, and his work on the production of an anti-polarising glass for safety spectacles in 1909–14 (the basis of sun-glasses) was one of many contributions to public welfare.

The most controversial aspect of Crookes's career was his investigation of mediums in the 1870s and 1880s. Following the death of a much-loved brother at sea (which also led him into a libel action) Crookes attended seances, becoming interested in the kinetic, audible, and luminous phenomena that could be witnessed in fashionable seances of the period. To the disgust of members of the scientific community such as W. B. Carpenter, J. Tyndall, and T. H. Huxley (but supported by A. R. Wallace), Crookes was persuaded that the mediumship of some practitioners was genuine. In 1870 he subjected D. D. Home to a number of tests, and convinced himself that Home possessed a psychic force that could be used to modify gravity, produce musical effects, and perform feats unknown to science or conjuring. When the Royal Society rejected his papers on the subject on the grounds that the experimental conditions were insufficiently exacting, Crookes reported them in his own Quarterly Journal of Science. Even more sensational was Crookes's support for the pretty young medium Florence Cook, who materialized a phantom called Katie King. Contemporary debate, that has continued to the present day, questions whether Crookes lied under the spell of infatuation. Was he duped; and, if he ever understood this, was he too embarrassed to confess? There can be no doubt of Crookes's sincerity or that he staked his very considerable scientific reputation on the validity of the extraordinary phenomena he described. He genuinely believed that a scientific investigation of psychic phenomena held out the promise of data and theories that were unseen and unknown in contemporary natural philosophy.

Crookes was a great experimentalist. His material discoveries were of lasting and fundamental value. His ventures into psychical research were strongly criticized by contemporaries and certainly led him into some curious company, but they demonstrate that he thought all natural phenomena worthy of investigation, and that he refused to be bound by tradition and convention. Although Lord Kelvin believed Crookes started more hares than any other scientific contemporary, he was a man of science in the broadest sense, an influential personality, and a doyen of his profession.

Crookes died at 7 Kensington Park Gardens, London, on 4 April 1919, less than three years after his wife, to whom he had been devoted, and was buried in Brompton cemetery six days later.

W. H. Brock


E. E. Fournier d’Albe, Sir William Crookes (1923) · W. H. Brock, ‘Crookes, William’, DSB · R. G. Medhurst and K. M. Goldney, ‘William Crookes and the physical phenomena of mediumship’, Proceedings of the Society for Psychical Research, 54 (1963–6), 25–157


Royal Institution of Great Britain, London, laboratory notebooks, papers · RS, letters to Royal Society · Sci. Mus., laboratory books · Sci. Mus., notebooks, letters, and papers |  Air Force Research Laboratories, Cambridge, Massachusetts, Strutt MSS · BL, letters to Alfred Russel Wallace, Add. MSS 46437–46442 · CUL, corresp. with Sir George Stokes · ICL, letters to Henry Armstrong; letters to S. P. Thompson · Sci. Mus., letters to C. H. Gimingham, assistant · Sci. Mus., corresp. with Oswald John Silberrad · Society for Psychical Research, London, corresp. with Sir Oliver Lodge · Wellcome L., letters to John Spiller


A. Ludovici, oils, c.1884–1885, NPG [see illus.] · G. C. Beresford, photograph, 1906, NPG · C. Dessler, bronze bust, 1908, RS · W. Strang, chalk drawing, 1910, Royal Collection · E. A. Walton, oils, 1911, RS · Elliott & Fry, photogravure photograph, NPG · Spy [L. Ward], caricature, chromolithograph, NPG; repro. in VF (21 May 1903) · W. Stoneman, photograph, NPG · five photographs, RS · photographs, priv. coll.; repro. in Fournier d'Albe, Sir William Crookes

Wealth at death  

£29,013 18s. 4d.: probate, 11 July 1919, CGPLA Eng. & Wales