Editing William Crookes (section)

===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