William Crookes

Crookes's life was one of unbroken scientific activity that extended over sixty-seven years. He was considered remarkable for his industriousness and for his intellectual qualities.{{cite journal |last1=Dyer |first1=B. |last2=Thorpe |first2=T. E. |last3=Harker |first3=J. A. |last4=Simmonds |first4=C. |last5=Perkin |first5=F. Mollwo |title=Obituary notices: Sir William Crookes, O.M., 1832–1919; Thomas Fairley, 1843–1919; Walter William Fisher, 1842–1920; Antoine Paul Nicolas Franchimont, 1844–1919; Harold Cecil Greenwood, 1887–1919; Charles Edward Groves, 1841–1920; John Holmes, 1871–1919; Sir Boverton Redwood, Bart., 1846–1919; John Charles Umney, 1868–1919 |journal=J. Chem. Soc., Trans. |date=1920 |volume=117 |pages=444–472 |doi=10.1039/CT9201700444}}

His experiments in chemistry and physics were known for the originality of their design, and he is considered a "superb experimentalist". His interests, ranging over pure and applied science, economic and practical problems, and psychic research, made him a well-known personality and earned him a substantial income. He received many public and academic honours.

William Crookes was born in London in 1832, the eldest of eight surviving children (eight others died young) of Joseph Crookes (1792–1889), a wealthy tailor and real estate investor of north-country origin, and his second wife, Mary (née Scott; 1806–1884).{{cite web| url = http://www.bshr.org.uk/journals/022%20RHHCT%20Journal%2022%202004.pdf| title = William Crookes: Covert Resources and a Mentor, 1871–81. By the late Derek R. Guttery.}}{{Cite ODNB|url=https://www.oxforddnb.com/view/10.1093/ref:odnb/9780198614128.001.0001/odnb-9780198614128-e-32639|title=Crookes, Sir William (1832–1919), chemist and science journalist|year=2004|doi=10.1093/ref:odnb/32639}} Joseph Crookes's father, William (1734–1814), was also a tailor, whose grandfather, John Crookes (b. 1660), had been Mayor of Hartlepool, County Durham on three occasions.William Crookes (1832–1919) and the Commercialization of Science, William H. Brock, Routledge, 2008; Routledge, pp. 3–4

Joseph Crookes had had five children with his first wife; two sons from that marriage, Joseph and Alfred, took over the tailoring business, leaving William free to choose his own path. In 1848, at age 16, Crookes entered the Royal College of Chemistry (now the Imperial College chemistry department) to study organic chemistry. Crookes lived with his parents about three miles from the College in Oxford Street. His father's shop was about half a mile away. Crookes paid £25 for his first year's tuition and had to provide his own apparatus and some of the more expensive chemicals. At the end of his first year, Crookes won the Ashburton scholarship which covered his second year's tuition. At the end of his second year, Crookes became a junior assistant to August Wilhelm von Hofmann, doing laboratory demonstrations and helping with research and commercial analysis. In October 1851, Crookes was promoted to senior assistant, a position he held until 1854.{{rp|8–10}}

Although Crookes revered Hofmann, he did not share his primary interest in organic chemistry.

One of Crookes's students was the Reverend John Barlow, Secretary of the Royal Institution, who chose to take a course in analytical chemistry. Through Barlow, Crookes met scientists such as George Gabriel Stokes and Michael Faraday.{{rp|11}}

Such friends reinforced Crookes's interest in optical physics{{rp|13}} which was respected by Hofmann.{{rp|12–13}}

By 1851, Crookes's interest in photography and optics caused his father to build him a laboratory in the garden at home for his research.{{rp|8}}

When Crookes embarked upon original work, it wasn't in organic chemistry, but rather into new compounds of selenium. These were the subject of his first published papers, in 1851. He worked with Manuel Johnson at the Radcliffe Observatory in Oxford in 1854, where he adapted the recent innovation of wax paper photography to machines built by Francis Ronalds to continuously record meteorological parameters.{{Cite book|title=Sir Francis Ronalds: Father of the Electric Telegraph|last=Ronalds|first=B.F.|publisher=Imperial College Press|year=2016|isbn=978-1-78326-917-4|location=London}} In 1855 he was appointed lecturer in chemistry at the Chester Diocesan Training College.{{cite book |last1=Ruoff |first1=Henry W. |title=Masters of achievement; the world's greatest leaders in literature, art, religion, philosophy, science, politics and industry |date=1910 |publisher=The Frontier press company |location=Buffalo, N.Y. |page=639 |url=https://books.google.com/books?id=kYo-AQAAIAAJ&pg=PA639 |access-date=7 December 2019}}

In April 1856 Crookes married Ellen, daughter of William Humphrey of Darlington. Since staff at Chester were required to be bachelors, he had to resign his position. William's father, Joseph Crookes, gave the couple a house at 15 Stanley Street, Brompton. Ellen's mother, Mrs. Humphrey, lived with them for the rest of her life, nearly forty years. A devoted couple, William and Ellen Crookes had six sons and three daughters. Their first child, Alice Mary (born 1857, later Mrs. Cowland) remained unmarried for forty years, living with her parents and working as an assistant to her father. Two of Crookes's sons became engineers, and two lawyers.

Married and living in London, Crookes sought to support his new family through independent work as a photographic chemist. In 1859, he founded the Chemical News, a science magazine which he edited for many years and conducted on much less formal lines than was usual for the journals of scientific societies. Between 1864 and 1869, he was also involved with the Quarterly Journal of Science. At various times he edited the Journal of the Photographic Society and the Photographic News.

File:William Crookes 7 Kensington Park Gardens blue plaque.jpg, London]]

Crookes was effective in experimentation. The method of spectral analysis, introduced by Bunsen and Kirchhoff, was received by Crookes with great enthusiasm and to great effect.{{cite journal|title = Spectroscopy and the Elements in the Late Nineteenth Century: The Work of Sir William Crookes|first = Robert K.|last = DeKosky|journal = The British Journal for the History of Science|volume = 6|issue = 4|date = 1973|pages = 400–423|jstor = 4025503|doi = 10.1017/S0007087400012553|s2cid = 146534210}}

File:Thallium sample.jpg, discovered by Crookes]]

File:Crookesite.jpg, a selenide of copper, thallium and silver ({{chem|Cu|7|(Tl|, Ag)|Se|4}}), named for Crookes]]

His first important discovery was that of the element thallium, made with the help of flame spectroscopy. Crookes discovered a previously unknown element with a bright green emission line in its spectrum. He named the element thallium, from Greek {{lang|el|θαλλός}}, {{lang|el-Latn|thallós}}, meaning "a green shoot or twig". Crookes's findings were published on 30 March 1861.Crookes, William (30 March 1861) "On the existence of a new element, probably of the sulphur group," Chemical News, vol. 3, [https://books.google.com/books?id=6QcAAAAAMAAJ&pg=PA193 pp. 193–194]; reprinted in: {{cite journal|url=https://books.google.com/books?id=OhyQnaPXF5QC&pg=RA1-PA301|date=April 1861|doi=10.1080/14786446108643058|title=XLVI. On the existence of a new element, probably of the sulphur group|volume =21|issue =140|pages =301–305|journal=Philosophical Magazine|last1=Crookes|first1=William}}Crookes, William (18 May 1861) "Further remarks on the supposed new metalloid," Chemical News, vol. 3, [https://books.google.com/books?id=6QcAAAAAMAAJ&pg=PA303 p. 303].Crookes, William (19 June 1862) "Preliminary researches on thallium," Proceedings of the Royal Society of London, vol. 12, pages 150–159.

Thallium was also independently discovered by Frenchman Claude Auguste Lamy, who had the advantage of access to large amounts of materials via his brother-in-law, Charles Frédéric Kuhlmann. Both Crookes and Lamy isolated the element in 1862.Lamy, A. (16 May 1862) "De l'existencè d'un nouveau métal, le thallium," Comptes Rendus, vol. 54, [http://gallica2.bnf.fr/ark:/12148/bpt6k30115.image.r=Comptes+Rendus+Hebdomadaires.f1254.langFR pages 1255–1262].{{cite journal | author = Weeks, Mary Elvira |author-link=Mary Elvira Weeks| title = The discovery of the elements: XVI. The rare earth elements | journal = Journal of Chemical Education | year = 1932 | volume = 9 | issue = 10 | pages = 1751–1773 | doi = 10.1021/ed009p1751 |bibcode = 1932JChEd...9.1751W }}{{cite journal| doi = 10.1021/ed009p2078| title = The discovery of the elements. XIII. Supplementary note on the discovery of thallium| date = 1932| last1 = Weeks| first1 = Mary Elvira|author-link1=Mary Elvira Weeks| journal = Journal of Chemical Education| volume = 9| issue = 12| page = 2078|bibcode = 1932JChEd...9.2078W }}

Crookes was elected a fellow of the Royal Society in 1863. Crookes wrote a standard treatise on Select Methods in Chemical Analysis in 1871.

In 1866, Adolf Erik Nordenskiöld identified a rare mineral from Skrikerum as a selenide of copper, thallium, and silver ({{chem|Cu|7|(Tl|, Ag)|Se|4}}), and named the mineral crookesite in honor of Sir William Crookes.{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}{{cite journal |last1=Marshall |first1=James L. Marshall |last2=Marshall |first2=Virginia R. Marshall |title=Rediscovery of the elements: Thallium, Crookes, and Lamy |journal=The Hexagon |date=2011 |pages=62–67 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/thallium.pdf |access-date=30 December 2019}}

Crookes developed the Crookes tube,The difference between "Crookes tubes" and "Geissler tubes" is this: In a Geissler tube the exhaustion is very much less than in a Crookes tube, the light which we see in the Geissler tube being due to the luminescence of the residual gas. (Transactions, Volume 9. Hertfordshire Natural History Society and Field Club. The Club, 1898. [https://books.google.com/books?id=cKoUAAAAYAAJ&pg=PA136 Page 136].) investigating cathode rays. He published numerous papers on spectroscopy and conducted research on a variety of minor subjects. In his investigations of the conduction of electricity in low pressure gases, he discovered that as the pressure was lowered, the negative electrode (cathode) 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). As these examples indicate, he was a pioneer in the construction and use of vacuum tubes for the study of physical phenomena.Alexander E. Outerbridge, Jr., A Fourth State of Matter. Lecture delivered before the Franklin Institute, 17 February 1881. Journal of the Franklin Institute of the State of Pennsylvania, Volume 81. By Franklin Institute (Philadelphia, Pa.). [https://books.google.com/books?id=2QFAAAAAYAAJ&pg=PA287 Page 287+]. He was, as a consequence, one of the first scientists to investigate what is now called a plasma and identified it as the fourth state of matter in 1879.William Crookes, On Radiant Matter. Lecture delivered before the British Association for the Advancement of Science, at Sheffield, Friday, 22 August 1879. The Popular Science Monthly, Volume 16. D. Appleton, 1880. [https://books.google.com/books?id=JM8WAQAAIAAJ&pg=PA157 Pg157+] He also devised one of the first instruments for studying nuclear radioactivity, the spinthariscope.Crookes, W. Certain Properties of the Emanations of Radium. Chemical News; Vol. 87:241; 1903.{{Cite web | last = Frame | first = Paul W. | title = The Crookes Spinthariscope | url = https://www.orau.org/health-physics-museum/collection/spinthariscopes/crookes-spinthariscope.html | publisher = Oak Ridge Associated Universities | access-date = 11 October 2021 }}{{cite book|author=Alfred Romer|title=The Restless Atom: The Awakening of Nuclear Physics|url=https://books.google.com/books?id=iHsKAAAAMAAJ|access-date=2 May 2013|year=1960|publisher=Anchor Books}}

File:Portrait of William Crookes as Hofmann's assistant.tiff | Portrait of William Crookes, age 18

File:Portrait of William Crookes, age 24.tiff | Portrait of William Crookes, age 24

File:Portrait of William Crookes, age 57.tiff | Portrait of William Crookes, age 57

File:Portrait of Sir William Crookes, O.M., age 79.tiff | Portrait of Sir William Crookes, O.M., age 79

File:Sir William Crookes 1902.jpg|Sir William Crookes by Sir Leslie Ward, 1902

Crookes investigated the properties of cathode rays, showing that they travel in straight lines, cause fluorescence when they fall on some substances, and that their impact can 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. [https://books.google.com/books?id=EEpUAAAAYAAJ&pg=PA43 Page 43+]. but his theoretical views on the nature of "radiant matter" were to be superseded.Chemist & Druggist, Volume 60. Benn Brothers., 1902. [https://books.google.com/books?id=uKQhAQAAMAAJ&pg=PA268 Pg 268]. 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.{{cite book |last1=Martz |first1=Harry E. |last2=Logan |first2=Clint M. |last3=Schneberk |first3=Daniel J. |last4=Shull |first4=Peter J. |title=X-ray imaging : fundamentals, industrial techniques, and applications |date=2016 |publisher=CRC Press |isbn=9780849397721 |page=27 |url=https://books.google.com/books?id=qxMNDgAAQBAJ&pg=PA27 |access-date=7 December 2019}}

Crookes's attention had been attracted to the vacuum balance in the course of his research into thallium. He soon discovered the phenomenon which drives the movement in a Crookes radiometer, in which a set of vanes, each blackened on one side and polished on the other, rotate when exposed to radiant energy. Crookes did not, however, provide the true explanation of this apparent "attraction and repulsion resulting from radiation".{{cite journal |first=William |last=Crookes |author-link=William Crookes |date=1 January 1874 |doi=10.1098/rstl.1874.0015 |title=On Attraction and Repulsion Resulting from Radiation |journal=Philosophical Transactions of the Royal Society of London |volume=164 |pages=501–527|s2cid=110306977 |url=https://zenodo.org/record/1432450 |doi-access=free }}.{{Cite journal|last=Lebedew|first=Peter|year=1901|title=Untersuchungen über die Druckkräfte des Lichtes|journal=Annalen der Physik|volume=311|issue=11|pages=433–458| doi=10.1002/andp.19013111102|bibcode=1901AnP...311..433L|url=https://zenodo.org/record/1424005}}{{US Patent|182172}}, Improvement in Apparatus For Indicating The Intensity of Radiation

File:Sir William Crooks in his laboratory. Wellcome M0004618.jpg

After 1880, Crookes lived at 7 Kensington Park Gardens in the fashionable area of Notting Hill. His household included a large multigenerational family and a number of servants. There all his later work was done, in what was then "the finest private laboratory in Britain". It comprised an entire floor of the house and included three interconnected laboratory rooms, for chemistry, physics, and mechanical construction, and a library. Crookes was able to purchase the house and build the laboratory because of his income from the National Guano Company and from various patents.{{cite book |last1=Brock |first1=William H. |title=William Crookes (1832–1919) and the Commercialization of Science |date=10 November 2016 |publisher=Routledge |isbn=978-1138259881 |pages=xxiii- |url=https://books.google.com/books?id=J-64DQAAQBAJ&pg=PT35 |access-date=7 December 2019}}{{rp|35}}

By 1880 Crookes employed a paid full-time scientific assistant (first Charles Gimingham and after 1883 James Gardiner). He was also helped by his daughter Alice, who was "adept at fractionating rare earth elements" and "no mean interpreter of spectra".

His daily routine was to manage his commercial affairs in the morning, do further business or go to scientific meetings in the afternoon, eat dinner at 7, work in his library from 8 to 9, and then in the laboratory until after midnight. From his home, Crookes could easily reach the Chemical News offices, the Royal Society, the Chemica Society, and the Athenaeum Club.

On 16 January 1884, Crookes's father died. Crookes's daughter Florence died of scarlet fever in the same week. Joseph Crookes's estate was left in trust, divided between his three surviving sons, Alfred, William and Frank. Combined with his previous income, this ensured that Crookes was very well off.

In 1886, Crookes was elected as a member to the American Philosophical Society.{{Cite web|title=APS Member History|url=https://search.amphilsoc.org/memhist/search?year=1886;smode=advanced;startDoc=61|access-date=24 May 2021|website=search.amphilsoc.org}}

File:Periodic table in the style of a space lemniscate william crookes slide.jpeg

On 13 August 1894, John William Strutt, 3rd Baron Rayleigh and William Ramsay announced the detection of a new gas in the atmosphere. On 31 January 1895 they made a full report to the Royal Society on the new gas, argon. In addition, William Crookes, who had been asked to examine a sample, presented on the spectra of argon, reported that argon displayed two distinct spectra. In this way, Crookes identified the first known sample of terrestrial helium and established its correspondence to observations of solar helium. The discovery of argon and of helium led to identification of the noble gases and the reorganization of the periodic system.{{cite journal |last1=Giunta |first1=Carmen J. |title=Argon and the Periodic System: the Piece that Would not Fit |journal=Foundations of Chemistry |date=2001 |volume=3 |issue=2 |pages=105–128 |doi=10.1023/A:1011464516139 |citeseerx=10.1.1.25.615 |s2cid=92514263 }}

Crookes himself suggested a design for a Periodic table in the style of a space lemniscate in 1898.{{cite web |title=Crookes' spiral periodic system |url=https://collection.sciencemuseumgroup.org.uk/objects/co13105 |website=Science Museum Group |access-date=12 December 2019}}{{cite web |last1=Leach |first1=Mark R. |title=3-Dimensional Periodic Table formulations |url=https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?Button=3D+Formulations |website=Internet Database of Periodic Tables |access-date=12 December 2019}}{{cite web |title=Periodic table in the style of a space lemniscate |url=https://digital.sciencehistory.org/works/pg15bf40t |website=Science History Institute |access-date=12 December 2019}}

Crookes was knighted in 1897.{{cite journal |last1=James |first1=Frank A. J. L. |title=Champion of Victorian Science |url=https://www.sciencehistory.org/distillations/champion-of-victorian-science |journal=Distillations |publisher=Science History Institute |date=11 April 2009 |access-date=23 August 2018 |archive-date=6 March 2022 |archive-url=https://web.archive.org/web/20220306181328/https://www.sciencehistory.org/distillations/champion-of-victorian-science |url-status=dead }}

Crookes was named president of the British Association for the Advancement of Science in 1898. In his inaugural address, he outlined in detail a coming catastrophe: The wheat-eating peoples of the world were going to start running out of food in the 1930s. The reason, he said, was a dearth of nitrogen fertilizer available from natural sources. Crookes called on chemists to develop new ways of making fertilizer from the enormous stock of nitrogen in the atmosphere (which is roughly 80 percent nitrogen). His remarks on the coming famine achieved wide distribution in the press and were turned into a popular book. Scientists addressing the problem in the first years of the twentieth century included Kristian Birkeland, whose technology helped found Norsk Hydro, and Fritz Haber and Carl Bosch, whose Haber–Bosch process forms the foundation of today's nitrogen fertilizer industry.{{cite book|first=Thomas|last=Hager|title=The Alchemy of Air|publisher=Three Rivers Press|location=New York City|date=2008|isbn=978-0-307-35179-1|pages=3–11}}

In 1903{{contradict inline|Protactinium#History|date=March 2024}}, 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).{{cite book |last1=Burns |first1=Peter C. |last2=Finch |first2=Robert J. |title=Uranium : mineralogy, geochemistry and the environment |date=7 May 2018 |publisher=Mineralogical Society of America |isbn=9780939950508 |page=6 |url=https://books.google.com/books?id=CbB6DwAAQBAJ&pg=PA6 |access-date=7 December 2019}} Crookes 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 detection of radioactivity.{{cite book |last1=Lincoln |first1=Donald |title=Understanding the universe : from quarks to the cosmos |date=2012 |publisher=World Scientific |isbn=9789814374453 |pages=26 |edition=Revisedition |url=https://books.google.com/books?id=Qwy7CgAAQBAJ&pg=PA26}}

In 1913, Crookes{{cite web|url=https://www.collinsdictionary.com/dictionary/english/crookes-lens|title=Crookes lens definition and meaning – Collins English Dictionary|website=www.collinsdictionary.com|access-date=3 June 2018}} created an ultraviolet blocking lens{{cite journal|title=Sir William Crookes' anti-glare glasses|first=J. H.|last=Gardiner|date=3 June 2018|journal=Transactions of the Optical Society|volume=24|issue=2|pages=102–103|doi=10.1088/1475-4878/24/2/310|bibcode=1923TrOS...24..102G}}{{cite book|url=https://books.google.com/books?id=Dd75mKOE4BMC&q=crookes&pg=PA464|title=William Crookes (1832-1919) and the Commercialization of Science|first=William Hodson|last=Brock|date=3 June 2018|publisher=Ashgate Publishing, Ltd.|access-date=3 June 2018|via=Google Books|isbn=9780754663225}} made from glass containing cerium,{{cite web|url=http://museyeum.org/results.php?name_title=Crookes&op-earliest_year==&op-latest_year==&module=objects&type=advanced|title=The College of Optometrists|website=museyeum.org|access-date=3 June 2018}} but only lightly tinted.{{cite web|url=https://www.opticianonline.net/features/optical-connnections-work-sir-william-crookes|date=3 June 2018|access-date=3 June 2018|archive-url=https://web.archive.org/web/20180603181459if_/https://webcache.googleusercontent.com/search?q=cache:g_lCrq0LVl4J:https://www.opticianonline.net/features/optical-connnections-work-sir-william-crookes|archive-date=3 June 2018|url-status=dead|title=Optical {{as written|conn|nections [sic]}}: The work of Sir William Crookes – Optician}} They were an unintended by-product of Crookes's research to find a lens glass formulation that would protect glass workers from cataracts.{{cite news|url=https://www.thetimes.com/uk/science/article/out-of-the-shade-t38jv5mbm3v|title=Out of the shade|date=9 November 2015|access-date=3 June 2018|via=www.thetimes.co.uk}} Crookes tested more than 300 formulations,{{cite web| url = https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnologicpaperT93e1.pdf| title = Coblentz, W. W.; Emerson, W. B. Glasses for protecting eyes from injurious radiations. (1st ed.) 1916-11-14}} NIST each numbered and labelled. Crookes Glass 246 was the tint recommended for glassworkers. The best-known Crookes tints are A (withdrawn due to its uranium), A1, B, and B2, which absorb all ultraviolet below 350 nm while darkening visual light. Crookes's samples were made by Whitefriars, London, stained glass makers, and Chance Brothers, Birmingham.{{cite web|url=http://museyeum.org/detail.php?name_title=Crookes&module=objects&type=advanced&kv=7151&record=18|title=Sir William Crookes' U "Ultimate" Anti-Glare Formula OPHTHALMIC LENSES tinted lens samples set, Sir William Crookes Anti-Glare Glass Co Ltd; Melson Wingate Ltd – British Optical Association Museum – The College of Optometrists|website=museyeum.org|access-date=3 June 2018}}{{cite web|url=http://museyeum.org/detail.php?name_title=Crookes&module=objects&type=advanced&kv=20397&record=21&module=objects|title=The Ultra-Violet Limit of Chance's 'Crookes' Glasses Compared with White Spectacle Glass and Some Common Tinted Glasses – Chance Brothers & Co. Ltd Smethwick, Birmingham, England 1920s (Promotional chart reproducing in black and white a spectral chart comparing various types of glass used for ophthalmic lenses. Landscape format, printed on one side only of a single sheet of white paper.) – British Optical Association Museum – The College of Optometrists|website=museyeum.org|access-date=3 June 2018}}{{cite web|url=https://patents.google.com/patent/US1634182A/en|title=Colorless crookes glass|website=google.com|access-date=3 June 2018}}

Crookes became interested in spiritualism in the late 1860s, and was most strongly involved around 1874–1875. Eric Deeson notes that Crookes's studies of the occult are related to his scientific work on radiometry in that both involved the detection of previously undiscovered forces.{{cite journal |last1=Deeson |first1=Eric |title=Commonsense and Sir William Crookes |journal=New Scientist |date=26 December 1974 |pages=922–925 |url=https://books.google.com/books?id=khzDRYfj97AC&pg=PA922 }}{{Dead link|date=May 2024 |bot=InternetArchiveBot |fix-attempted=yes }}

Crookes was possibly influenced by the death of his younger brother Philip in 1867 at 21 from yellow fever contracted while he was on an expedition to lay a telegraph cable from Cuba to Florida.Janet Oppenheim. (1988). The Other World: Spiritualism and Psychical Research in England, 1850–1914. Cambridge University Press. pp. 343–347. {{ISBN|978-0521265058}}John Hannavy. (2007). Encyclopedia of Nineteenth-Century Photography. Routledge. p. 350. {{ISBN|978-0415972352}} "Crookes' beloved younger brother had died in 1867 and the scientist hoped that spiritualism could provide a reunion. Although warned of the risk of ridicule, Crookes announced his intent to investigate mediums."

In 1867, influenced by Cromwell Fleetwood Varley, Crookes attended a séance to try to get in touch with his brother.Sherrie Lynne Lyons. (2010). Species, Serpents, Spirits, and Skulls: Science at the Margins in the Victorian Age. State University of New York Press. p. 92. {{ISBN|978-1438427980}} "Crookes appears to have been initially attracted to spiritualism when his youngest brother, whom he was quite close to, died of yellow fever. Brought up with the traditional Christian belief in the afterlife, Crookes was persuaded to attend a séance in 1867 to try to make contact with his brother."Martyn Jolly. (2006). Faces of the Living dead: The Belief in Spirit Photography. Miegunyah Press. p. 30. {{ISBN|978-0712348997}} "In 1867, he was devastated by the death of his much-loved youngest brother who, at the age of twenty-one. had caught yellow fever while laying a submarine telegraph cable in Cuba. At the time, Crookes was collaborating with a fellow electro-physicist Cromwell Fleetwood Varley, who was a pioneer of intercontinental telegraphy, as well as a clairvoyant. He persuaded Crookes to try to get in touch with his dead brother by spiritualist means."

Between 1871 and 1874, Crookes studied the mediums Kate Fox, Florence Cook, and Daniel Dunglas Home. After his investigation, he believed that the mediums could produce genuine paranormal phenomena and communicate with spirits.Daniel Cohen. (1971). Masters of the Occult. Dodd, Mead & Company. p. 111. {{ISBN|978-0396064077}}Andrew Neher. (2011). Paranormal and Transcendental Experience: A Psychological Examination. Dover Publications. p. 214. {{ISBN|978-0486261676}} "William Crookes, the noted English physicist, had endorsed Catherine Fox as genuine... Crookes also endorsed several other mediums who were later exposed, including Anna Eva Fay (who was exposed more than once and who eventually explained how she duped Crookes), Florence Cook (who was the subject of more than one expose), and D. D. Home." Psychologists Leonard Zusne and Warren H. Jones have described Crookes as gullible as he endorsed fraudulent mediums as genuine.Leonard Zusne; Warren H. Jones. (2014). Anomalistic Psychology: A Study of Magical Thinking. Psychology Press. p. 216. {{ISBN|978-0-805-80508-6}} "The fact is that William Crookes, although very good at physics experiments, was rather weak on drawing inferences and on theorizing. Besides, he was gullible. He endorsed several mediums in spite of their demonstrated trickery. Having witnessed a single seance with Kate Fox, he became convinced that the Fox sisters' rappings were genuine."

File:William Crookes Katie King.png

The anthropologist Edward Clodd noted that Crookes had poor eyesight, which may have explained his belief in spiritualist phenomena and quoted William Ramsay as saying that Crookes is "so shortsighted that, despite his unquestioned honesty, he cannot be trusted in what he tells you he has seen."Edward Clodd. (1917). The Question: A Brief History and Examination of Modern Spiritualism. Grant Richards, London. p. 100 Biographer William Hodson Brock wrote that Crookes was "evidently short-sighted, but did not wear spectacles until the 1890s. Until then he may have used a monocle or pocket magnifying glass when necessary. What limitations this imposed upon his psychic investigations we can only imagine."{{rp|140}}

After studying the reports of Florence Cook, the science historian Sherrie Lynne Lyons wrote that the alleged spirit "Katie King" was at times Cook herself and at other times an accomplice. Regarding Crookes, Lyons wrote, "Here was a man with a flawless scientific reputation, who discovered a new element, but could not detect a real live maiden who was masquerading as a ghost".Sherrie Lynne Lyons. (2010). Species, Serpents, Spirits, and Skulls: Science at the Margins in the Victorian Age. State University of New York Press. p. 101. {{ISBN|978-1438427980}} Cook was repeatedly exposed as a fraudulent medium but she had been "trained in the arts of the séance" which managed to trick Crookes.M. Lamar Keene. (1997). The Psychic Mafia. Prometheus Books. p. 64. {{ISBN|978-1573921619}} "The most famous of materialization mediums, Florence Cook-- though she managed to convince a scientist, Sir William Crookes, that she was genuine-- was repeatedly exposed in fraud. Florence had been trained in the arts of the séance by Frank Herne, a well-known physical medium whose materializations were grabbed on more than one occasion and found to be the medium himself." Some researchers such as Trevor H. Hall suspected that Crookes had an affair with Cook.Trevor H. Hall. (1963). The Spiritualists: The Story of Florence Cook and William Crookes. Helix Press.{{cite journal |last1=Brandon |first1=Ruth |title=Unsavoury Spirits |journal=New Scientist |date=18 July 1985 |page=52 |url=https://books.google.com/books?id=p6DGWU27baYC&pg=PA52 }}{{Dead link|date=May 2024 |bot=InternetArchiveBot |fix-attempted=yes }}{{cite journal |last1=Brandon |first1=Ruth |title=Scientists and the Supernormal |journal=New Scientist |date=16 June 1983 |pages=783–786 |url=https://books.google.com/books?id=BX7c6gVuyVQC&pg=PA783 }}{{Dead link|date=May 2024 |bot=InternetArchiveBot |fix-attempted=yes }}John Sladek. (1974). The New Apocrypha: A Guide to Strange Sciences and Occult Beliefs. Panther. p. 194. {{ISBN|978-0586039748}} "Crookes was forty-one, and his wife was pregnant with their tenth child. Florence was eighteen and pretty, and willing to spend considerable time at Crookes home, locked into a dark room alone with him, while beautiful apparitions were shown to him. The man Florence had secretly married, Captain Corner, put an unspiritual construction on the proceedings, and gave Crookes a beating. By 1875 the situation was becoming obvious to outsiders, who published hints that the next manifestation might be an infant phenomenon. As for the apparitions, no one but Crookes is reported to have ever seen them ... By 1880 Florence had been exposed as a fraud by Sir George Sitwell."Amy Lehman. (2009). Victorian Women and the Theatre of Trance: Mediums, Spiritualists. McFarland. p. 158. {{ISBN|978-0786434794}} Crookes took 44 photographs of "Katie King", in some of which he, or Florence Cook appear alongside her. He described in detail the physical differences between the spirit and her medium. The fact that some of these photographs, which still exist, show a Katie King who looks almost identical to Florence Cook calls Crookes's judgment, not to mention his veracity, into question. Skeptics at the time who were convinced that Florence was a fake thought that either Crookes was being completely hood-winked or that he had agreed to perpetrate the fraud with Florence. And the only explanation in either case had to be that Crookes was smitten with Florence—at the very least besotted with her and probably having an affair."

In a series of experiments in London, England at the house of Crookes in February 1875, the medium Anna Eva Fay managed to fool Crookes into believing she had genuine psychic powers. Fay later confessed to her fraud and revealed the tricks that she had used.Massimo Polidoro. (2000). Anna Eva Fay: The Mentalist Who Baffled Sir William Crookes. Skeptical Inquirer 24: 36–38. Regarding Crookes and his experiments with mediums, the magician Harry Houdini suggested that Crookes had been deceived.Harry Houdini. (2011, originally published 1924). A Magician Among the Spirits. Cambridge University Press. p. 205. {{ISBN|978-1108027489}} "There is not the slightest doubt in my mind that this brainy man was hoodwinked, and that his confidence was betrayed by the so-called mediums that he tested. His powers of observation were blinded and his reasoning faculties so blunted by his prejudice in favor of anything psychic or occult that he could not, or would not, resist the influence." The physicist Victor Stenger wrote that the experiments were poorly controlled and "his desire to believe blinded him to the chicanery of his psychic subjects."Victor J. Stenger. (1990). Physics and Psychics: The Search for a World Beyond the Senses. Prometheus Books. pp. 156–157. {{ISBN|978-0-87975-575-1}}

In 1897, John Grier Hibben wrote that Crookes's idea of ether waves explaining telepathy was not a scientific hypothesis "he presents no facts to indicate its probability or to save it from being relegated to the sphere of bare conjecture."Hibben, J. G. (1897). Review of Presidential Address to the Society for Psychical Research, by W. Crookes. Psychological Review 5: 362–387.

In 1916, William Hope tricked Crookes with a fake spirit photograph of his wife. Oliver Lodge revealed there had been obvious signs of double exposure, the picture of Lady Crookes had been copied from a wedding anniversary photograph, but Crookes was a convinced spiritualist and claimed it was genuine evidence for spirit photography.{{rp|474}}

The physiologist Gordon Stein suspected that Crookes was too ashamed to admit he had been duped by the medium Florence Cook or that he conspired with her for sexual favors. He also suggested that Crookes had conspired with Anna Eva Fay. He noted that contrary to popular belief, Hope had been exposed as a fraud on several occasions. Stein concluded that all feats of Hope were conjuring tricks.{{cite book |last1=Stein |first1=Gordon |title=The sorcerer of kings : the case of Daniel Dunglas Home and William Crookes |date=1993 |publisher=Prometheus Books |isbn=0-87975-863-5}} In a review, biographer William Brock wrote that Stein made his "case against Crookes and Home clearly and logically."Brock, William. (1994). [http://www.readcube.com/articles/10.1038/367422a0 Was Crookes A Crook?]. Nature 367: 422–422.

Crookes 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.{{rp|440}} In 1890 he was initiated into the Hermetic Order of the Golden Dawn.{{cite book |author=Alex Owen |title=The Place of Enchantment: British Occultism and the Culture of the Modern |pages=70 |year=2007 |location=Chicago |publisher=University of Chicago Press}}

• List of presidents of the Royal Society

{{Reflist}}

• {{ODNBweb| title=Crookes, Sir William (1832–1919) | author=William Hodson Brock | doi=10.1093/ref:odnb/32639 | year=2004 }}
• Edmund Edward Fournier d'Albe (2011, originally published in 1923). The Life of Sir William Crookes. Cambridge University Press. {{ISBN|978-1-108-06159-9}}

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• {{Gutenberg author | id=5544}}
• {{Internet Archive author |sname=William Crookes |sopt=t}}
• Crookes's (1874) [http://lhldigital.lindahall.org/cdm/ref/collection/color/id/13351 A practical handbook of dyeing and calico-printing] {{Webarchive|url=https://web.archive.org/web/20170729055002/http://lhldigital.lindahall.org/cdm/ref/collection/color/id/13351 |date=29 July 2017 }} – digital facsimile from the Linda Hall Library

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{{Copley Medallists 1901-1950}}

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