CROOKES, SIR WILLIAM, an Eng lish physicist and chemist; born in Lon don in 1832; studied at the Royal College of Chemistry under Hofmann, and after 1851 devoted himself to original re searches in science. He invented the radiometer in 1875, and the otheoscope in 1877, and announced in 1879 his dm covery of the fourth or ultra-gaseous state of matter. In 1880 the French Academie des Sciences bestowed on him an extraordinary prize of 3,000 francs and a gold medal in recognition of his discoveries in molecular physics and ra diant matter. In 1881 he acted as juror at the International Exhibition of Electric ity in Paris. In this official position he was not entitled to a medal, but in the official report his fellow jurors, after discussing the merits of four systems of incandescent lamps, declared—"None of them would have succeeded had it not been for these extreme vacua which Mr. Crookes has taught us to manage." It is stated that he was the first to apply photography to the investigation of the solar spectrum. He is the 'author of
"Select Methods in Chemical Analysis," "Manufacture of Beet-root Sugar in England," "Handbook of Dyeing and Calico-Printing," "Manual of Dyeing and Tissue-Printing," etc. He is also joint author of the English adaptation of Kerl's "Treatise on Metallurgy." He has edited the last three editions of Mitchell's "Manual of Practical Assay ing," and has translated into English and edited Reimann's "Aniline and its Derivatives," Wagner's "Chemical Tech nology," Auerbach's "Anthracen and its Derivatives," and Ville's "Artificial Ma nures." He is an authority on sanitary questions, especially the disposal of town-sewage. In 1907 he shared the Nobel prize for Chemistry with E. Buch per, and in 1910 was awarded the Order of Merit. He died on April 4, 1919.