Editing William Crookes (section)

==Biography==
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.<ref name="Obituary">{{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}}</ref> 
His experiments in chemistry and physics were known for the originality of their design,<ref name="Brock"/> and he is considered a "superb experimentalist".<ref name="Distillations"/> 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.<ref name="Obituary"/><ref name="Brock"/>

===Early years===
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).<ref>{{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.}}</ref><ref>{{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}}</ref> 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.<ref name="auto">William Crookes (1832–1919) and the Commercialization of Science, William H. Brock, Routledge, 2008; Routledge, pp. 3–4</ref>

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.<ref name="auto"/> 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.<ref name="Brock"/>{{rp|8–10}}

Although Crookes revered Hofmann, he did not share his primary interest in [[organic chemistry]].<ref name="Brock"/> 
One of Crookes's students was the Reverend [[John Barlow (priest)|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]].<ref name="Brock"/>{{rp|11}}
Such friends reinforced Crookes's interest in [[optical physics]]<ref name="Brock"/>{{rp|13}} which was respected by Hofmann.<ref name="Brock"/>{{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.<ref name="Brock"/>{{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 John Johnson|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 [[Photography#Science and forensics|continuously record]] meteorological parameters.<ref>{{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}}</ref> In 1855 he was appointed lecturer in chemistry at the [[University of Chester|Chester Diocesan Training College]].<ref name="Ruoff">{{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}}</ref>

In April 1856 Crookes married Ellen, daughter of William Humphrey of Darlington.<ref name=EB1911/> 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, London|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.<ref name="Brock"/>

Married and living in London, Crookes sought to support his new family through independent work as a photographic chemist.<ref name="Brock"/> 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''.<ref name="Brock"/>

===Middle years===
[[File:William Crookes 7 Kensington Park Gardens blue plaque.jpg|thumb|Blue plaque, 7 [[Ladbroke Square|Kensington Park Gardens]], London]]
Crookes was effective in experimentation. The method of [[Spectroscopy|spectral analysis]], introduced by [[Robert Bunsen|Bunsen]] and [[Gustav Kirchhoff|Kirchhoff]], was received by Crookes with great enthusiasm and to great effect.<ref name="Obituary"/><ref name="Brock"/><ref name="Marshall"/><ref name="Weeks"/><ref name="DeKosky">{{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}}</ref>

[[File:Thallium sample.jpg|right|thumb|The element [[thallium]], discovered by Crookes]]
[[File:Crookesite.jpg|thumb|right|The mineral [[crookesite]], a selenide of copper, thallium and silver ({{chem|[[Copper|Cu]]|7|([[Thallium|Tl]]|, [[Silver|Ag]])|[[Selenium|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 language|Greek]] {{lang|el|θαλλός}}, {{lang|el-Latn|[[thallus|thallós]]}}, meaning "a green shoot or twig". Crookes's findings were published on 30 March 1861.<ref name="Brock"/><ref name="Marshall"/><ref name="Weeks"/><ref name="DeKosky"/><ref>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}}</ref><ref>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].</ref><ref>Crookes, William (19 June 1862) "Preliminary researches on thallium," ''Proceedings of the Royal Society of London'', vol. 12, pages 150–159.</ref>

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.<ref name="Marshall"/><ref>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].</ref><ref>{{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 }}</ref><ref>{{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 }}</ref><ref name="DeKosky"/>

Crookes was elected a fellow of the ''Royal Society'' in 1863.<ref name="Obituary"/><ref name="Brock"/><ref name="Weeks"/> Crookes wrote a standard treatise on ''Select Methods in Chemical Analysis'' in 1871.<ref name="Brock"/>

In 1866, [[Adolf Erik Nordenskiöld]] identified a rare mineral from Skrikerum as a selenide of copper, thallium, and silver ({{chem|[[Copper|Cu]]|7|([[Thallium|Tl]]|, [[Silver|Ag]])|[[Selenium|Se]]|4}}), and named the mineral [[crookesite]] in honor of Sir William Crookes.<ref name="Weeks">{{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 }}</ref><ref name="Marshall">{{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}}</ref>

Crookes developed the [[Crookes tube]],<ref>The difference between "Crookes tubes" and "[[Geissler tube]]s" 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].)</ref> investigating [[cathode ray]]s. 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 [[electron]]s, and used in [[cathode-ray display device]]s). As these examples indicate, he was a pioneer in the construction and use of [[vacuum tube]]s for the study of physical phenomena.<ref>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+].</ref> He was, as a consequence, one of the first scientists to investigate what is now called a [[plasma (physics)|plasma]] and identified it as the fourth state of matter in 1879.<ref>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+]</ref> He also devised one of the first instruments for studying nuclear [[Radioactive decay|radioactivity]], the [[spinthariscope]].<ref name="Brock"/><ref>Crookes, W. Certain Properties of the Emanations of Radium. Chemical News; Vol. 87:241; 1903.</ref><ref>{{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 }}</ref><ref name="Romer1960">{{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}}</ref>

<gallery>
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 [[Leslie Ward|Sir Leslie Ward]], 1902
</gallery>

Crookes investigated the properties of [[cathode ray]]s, 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",<ref>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+].</ref> but his theoretical views on the nature of "radiant matter" were to be superseded.<ref>Chemist & Druggist, Volume 60. Benn Brothers., 1902. [https://books.google.com/books?id=uKQhAQAAMAAJ&pg=PA268 Pg 268].</ref> 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 [[electrons]]<ref>Negatively electrified particles whose mass is only 1/1840 that of a [[hydrogen]] atom</ref>). Nevertheless, Crookes's experimental work in this field was the foundation of discoveries which eventually changed the whole of chemistry and physics.<ref name="Martz">{{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}}</ref>

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]]".<ref>{{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 }}.</ref><ref name=":0">{{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}}</ref><ref>{{US Patent|182172}}, Improvement in Apparatus For Indicating The Intensity of Radiation</ref>

[[File:Sir William Crooks in his laboratory. Wellcome M0004618.jpg|thumb|right|Sir William Crookes in his laboratory]]
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.<ref name="Brock">{{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}}</ref>{{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 [[spectrum|spectra]]".<ref name="Brock"/>

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.<ref name="Brock"/>

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.<ref name="Brock"/>

In 1886, Crookes was elected as a member to the [[American Philosophical Society]].<ref>{{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}}</ref>

===Later years===
[[File:Periodic table in the style of a space lemniscate william crookes slide.jpeg|right|thumb|Sample illustration: Periodic table in the style of a space lemniscate by William Crookes]]
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]]<ref name="Giunta"/> and established its correspondence to observations of solar helium.<ref name="Obituary"/> The discovery of argon and of helium led to identification of the [[noble gases]] and the reorganization of the [[periodic system]].<ref name="Giunta">{{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 }}</ref> 
Crookes himself suggested a design for a Periodic table in the style of a space lemniscate in 1898.<ref>{{cite web |title=Crookes' spiral periodic system |url=https://collection.sciencemuseumgroup.org.uk/objects/co13105 |website=Science Museum Group |access-date=12 December 2019}}</ref><ref name="Leach">{{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}}</ref><ref>{{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}}</ref>
Crookes was knighted in 1897.<ref name="Distillations">{{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 }}</ref>

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.<ref name=Hager>{{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}}</ref>

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]]).<ref name="Burns">{{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}}</ref> Crookes observed the gradual [[Radioactive decay|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.<ref name="Lincoln">{{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}}</ref>

In 1913, Crookes<ref>{{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}}</ref> created an ultraviolet blocking lens<ref>{{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}}</ref><ref>{{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}}</ref> made from glass containing [[cerium]],<ref>{{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}}</ref> but only lightly tinted.<ref>{{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}}</ref> They were an unintended by-product of Crookes's research to find a lens glass formulation that would protect glass workers from cataracts.<ref name="The Times">{{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}}</ref> Crookes tested more than 300 formulations,<ref>{{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]]</ref> 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&nbsp;nm while darkening visual light. Crookes's samples were made by Whitefriars, London, stained glass makers, and Chance Brothers, Birmingham.<ref>{{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}}</ref><ref>{{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}}</ref><ref>{{cite web|url=https://patents.google.com/patent/US1634182A/en|title=Colorless crookes glass|website=google.com|access-date=3 June 2018}}</ref><ref name="The Times"/> he died in 1919 at age 86