572 SIR WILLIAM CROOKES. 



Sir William Crookes. — The death of Sir William 

 Crookes, O.M., D.Sc, F.R.S., on the 4th April, 1919, removes 

 from the scientific world one of the most distinguished chemists 

 of last century. He was born 87 years ago, and received his 

 chemical training at the Royal College of Chemistry, London, 

 under the direction of A. W. Hofmann. He subsequently be- 

 came Hofmann's assistant, and later on was appointed on the 

 staff of the Radclift'e Observatory at Oxford. He also had an 

 appointment at Chester Training College for a short time. The 

 first publication dealing with his scientific investigations appeared 

 as far back as 1851, and ten years later, when the spectroscope 

 was yet novel, and Bunsen and Kirchhofif's investigations by its 

 means had but recently brought new elements to light, Crookes 

 successfully employed this appliance for the discovery of the 

 metal thallium. His spectroscopic researches were followed by 

 his investigations regarding radiant matter, for which the French 

 Academy of Sciences awarded him 3,000 francs and a gold 

 medal. Then came a series of researches into the production 

 of high vacua, leading ultimately to the commercial manufac- 

 ture of the electric lamp. Crookes was the first to adopt electric 

 lighting in his own home, using for this purpose electric lamps 

 which he himself had made. 



With Crookes the (borderland between chemistry and physics 

 was a favourite field for exploration. Many will, for instance, 

 recollect the first appearance of Crookes' radiometer, in which 

 revolving vanes were set in motion, it was supposed, by light- 

 pressure, the phenomenon being really thermal, as Tait and 

 Dewar subsequently proved. In recent years Sir William devised 

 the spinthariscope to render visible the bombarding efifect of the 

 a-particles projected from radium. When Ramsay discovered 

 helium in cleveite it was Crookes to whom he submitted the gas, 

 and who identified it by means of the yellow D3 line. Just 40 

 years ago he began the study of electric discharges in high 

 vacua, and all the phenomena that are grouped around the 

 Crookes tube began to excite widespread interest and astonish- 

 ment. 



Crookes visited South Africa for the first time in 1896, and 

 took part in the famous legal proceedings relating to the 

 MacArthur-Forrest cyanide process for gold recovery. During 

 that visit he lectured in Johannesburg on the liquefaction of 

 gases. 



In 1898 Sir William aroused considerable interest, almost 

 sensational, by his famous address on " The Wheat Problem," 

 delivered before the British Association, in which he added the 

 role of economist to those of physicist, chemist, and mystic. 

 He pointed to prospective nitrogen famine as a world-danger 

 looming into view, and suggested aversion of that danger by 

 what is now well known as the fixation of atmospheric nitrogen. 

 As long ago as 1892 Sir William had demonstrated by experi- 

 ment that, by means of a strong induction current, air could be 

 made to burn, producing nitrogen and nitric acids, and, when re- 



