CKOOKES. 605 CROQUET. of Chemical Axriltisis (4th ed.. 1804) : an Kiif;- )isli translation of Wagner's Clicmiiijl Tevhnul- vijy (2U eil., ISiU) ; and pajjers on radiant-niallur s|)ectrosc'0])y. His original views on the genesis of the elements may, with the developnuMit of knowledge, form an important eoutribution to chcmieal philosophy. CROOKES TUBE. A sealed vessel of glass from whieh tlie air has been exhausted and a liigh vaeuum obtained, through whieh a eurrent from an induelion eoil or other source of high- jiotcntial eleetrieity is passed. A Crookes tnbe difters from a Oei-ssler tube (q.v.) in the higher degree of its exhaustion and in several impor- tant particulars whieh will appear in the de- scription of its operation given below. The name is derived from Sir, William Crookes (q.v.), who was able by his improvements in the Spren- gel pump (see Atu-Pujip) to obtain vacuum tubes of greater efficiency than those of previous investigators. Ciookes was not the inventor of the highly exhausted tube, as Hittorf, of Miin- ster (1S69), had perf<nined a number of experi- ments with tubes having a comparatively high vacuum, but it remained for the Knglish in- vestigator to push the experiments still further and to formulate hypotheses and theories. A Crookes tube contains two or more elec- trodes knowni as the cathodes and anodes. These are formed liy platinum wires which pass through the glass walls of the tube and terminate in metallic plates of the material and shape de- sired for the experiment. The exhaustion is effected by connecting the tube to a mercurial air- pump and then sealing it when the ])ro])er point is reached. The terminals are then connected with an induction coil which is set in operation. The important peculiarity of such a vacuum tube noticed by Professor Hittorf consists of a fluorescence (q.v.) or golden-green glow pro- duced on the glass opposite the cathode. There is not the brilliancy of glow that is found throughout the tube as in the Geissler tube, and ' the rays which produce the fluorescence issue from the surface of the cathode in straight lines normal or perpendicular to that surface, not being bent to follow the shape of the tube, a.s would be seen in ttibes of a less degree of ex- haustion. These cathode rays have many other interesting properties. They may be deflected by a magnet, and they catise a ntmiber of sub- stffnces, such as diamonds and rubies, on which they impinge, to become brilliantly pliosphores- cent ; their energy- is sufficient to heat to a liigli temperature a surface on which they fall and can also be exhibited in causing a small wheel with mica vanes, mounted within the tube, to revolve as a result of the im])aet. Crookes used cathodes of plane, convex, and concave stir- face, from which the rays would be emitted in beams either parallel, diverging, or converging. After studying these rays and their (iroperties he concluded that the discharge from the cathode represented a new form of matter which he con- sidered as existing in an ultra-gaseous or radiant state. The most important use of the Crookes tube is for the production of Rontgen rays, or X-rays (q.v.), which are the rays passing out from the tube opposite the cathode. To produce these rays a tube must be employed where the vacuum is adapted to the work in hand, and there are self-regulating tubes on tlie market in which this property is obtained. See Klectri- ciTV for an accotmt of the passage of a current thr<iigli-ra relied gases. CROOKES VACUUM. See M.vtter, Section on 'riirorirs iif Matter. CROOKSTON, kri.iks'lon. A city and the counly-seat of Polk County, Minn., in the north- western part of the State; on the Ked Lake River, which aft'ords abundant water-power, and on the (Jreal Northern 'and the Northern Pacilic railroads (Map: Jlinnesota, li .'!). It contains a line court - house and nuniieipal buildings, Crookston and Button business colleges, a gym- nasium, and a public library. The city derives a considerable trade from a tributary agricul- tural country, and manufactures lumber, farm machinery, wagons, carriages, sleighs, etc. Set- tled in J 872, Crookston was incorporated in 1879. The government is administered under a charter of 1883, which jirovidcs for a mayor, annuallv elected, and a nuinicii)al ciMincil. Popu- lation, in 1890, .3457; in 1900, 5359, CROP'PIES. A derisive nickname given by the Protestant Irish to their Catholic opponents in the time of the English Revolution of 1C88. The name refers to the tonsure of the [jriests. The Roundheads were so called in 1642. There is a factional Irish song called "Croppies Lie Down!" wnich is a favorite with Orangemen. CROP'SEY, .Jasper Fra.vcis (1823-1900). An American painter, born at Kossville, N. Y. At first lie studied architecture, but he abandoned it to study art under Edward JIatiry, and in 1847 visited Italy, where he painted "The Pon- tine Marshes" and other pieces. Afterwards he spent seven years in London, and exhibited at the Royal Academy. His "Autumn on the Hudson" and "Richmond Hill" were praised by .lohn Ruskin. After his return to America he lived in jSTew York City and at Hastings-on-the Hudson. Cropsey's work is old-fashioned now, but he was one of the best of the so-called 'Hud- son River School.' His subjects are well com- posed and his coloring not without merit, al- though hard and often crude. Other pictures by him are; "Niagara Falls;" "Peace;" "War;" "The Sibyl's Temple;" and "High Tom, Rock- land Lake." CROQUEMITAINE, kr6k'm6'tan' (Fr., from croquer, to crunch). A French monster or bogy invoked by nurses to frighten unruly children. In L'Epine's Legende de Croquemitaine, Mi- taine, a goddaughter of Charlemagne, goes in search of the Castle of Croquemitaine, near Saragossa. CROQUET, kro-kri' (apparently a variant of Fr. crochft, hook). No other open-air game played to-day has had such strange fluctuations of fortune as croquet. It was a favorite game at the courts of kings two hundred years ago, yet by the end of the eighteenth century it had sunk into oblivion, and. except in a remote ])or- tion of Ireland, had been forgotten and unprac- ticed. From that country it was retrans]>orted across the Channel to England some time pre- vious to 1800, and then the playing of the game became again so popular for twenty years as to assume the proportions of a national game. It had its national a.ssociation. and in every hamlet the click of the croquet-hall was to be heard. It traveled over the Atlantic, where it was almost as popular, and by ISK:! if demanded
