KESSEL. 463 KETONES. and acquired reputation as a portrait painter, but also treated historical and all those subjects wUieli liis father cultivated, and was made Court painter by Charles It. in ltJ80. His portrait of Philip IV. is in the Museum, and two mytholog- ical scenes, "Psyche Found by Cupid" and ■'Psyche Surrounded bj- Wild Animals," are in the Alcazar at Madrid. — .J.vN Tiio.M..s (Xieolaes) (1077-1741), nephew and pujiil of Ferdinand, was a L'enre painter in the manner of David Teniers, and, through his villnire festivals, became well known in Paris, whitlicr he had gone early in life. In 1704 ho returned to Antwerp to buy his mastership. Subsequently inheriting his uncle's property, he fell info dissipation and died in want. — Another Jax van Kessel (c.l(i41-!l0) , who was born and died at Amsterdam, painted landscapes in the manner of .Jacob Kuisdael and Hobbema. His winter landscapes and his views of Amsterdam are particularly valued, and may be seen in the museums at Amsterdam, Kotter- dani, Anluer]). Darmstadt, and in the Old Pina- kothek at JIunich. — TiiEouoRUS VAX Ke.ssel ( c. 1 U20- ? ) . engraver and etcher, boi-n in Hol- land, settled at Antwerp in 1052 and is kno«ii by etchings after Kubens, Van Dyck, Titian, Guido Reni, and others. These last two van Kes- sels were probably not related to the Antwerp family. KES'TREL. One of the smallest of the true falcons or 'nolde' bii'ds of prey (Falco alau- ihiriiis) , scarcely more than a foot in length, and the commonest of all the British Aecipitres. It is widely distributed in the Old World, occur- ring in Asia and Xorth Africa as well as in nearly all Europe. It is nearly related to the common s])arrow-hawk of America, which it re- sembles in color and habits, as well as in size. The general color is brick-red above. InifT. fawn, or rufous beneath, everywhere marked with black, and with the head and rump bluish-gray. The sexes differ markedly in color, the female tending toward rusty-brown, and the male toward asliy- gray. Like all true falcons, the kestrel is a strong flier, but it is easily distinguished from other falcons and hawks in" its habit of hovering in one spot for some time, sustaining itself by the rapid movement of the wings. When didng this, it always keeps its head to the wind, whence has arisen one of its popular names, 'windhover.' Like the sparrow-hawk, the kestrel is a very useful binl. its princi])al diet being mice and in- sects, in tlie destruction of which it renders real sendee to the farmers. It occasionally captures small birds, and can be trained to ilo so, but its use in falconry was always confined to the lower classes, among whom the use of the larger falcons was forbidden. For this reason, the name 'kes- trel' came to be applied as a term of contempt. The nest is made in hollow trees, in crevices of cliffs, or even in deserted crows' nests, and the eggs are usually about five in number, creamy white, more or less spotted with brown. See Plate of Falcons and Falconry. KESWICK, kezlk. A market-town in Cum- berland, Kngland, at the northern extremity of Derw cutwater, and at the foot of Skiddaw Mountain. 22 miles south-southwest of Carlisle (Man: England. C 2). It is a favorite tourists' resort, a centre of picturesque scenery, and con- tains the residence and burial-place of Souther. There are manufactures of coarse woolen cloth and blankets. Silver, lead, and zinc ores are mined, and Keswick is well known for its manu- factures of lead-pencils. The town owns its water and electric lighting supplies. Population,, in lilOl, 4450. KETCH (from Turk, qcdq, qalq, boat). A. small sailing vessel of 50 to .300 tons, formerly quite common in the Mediterranean, but now not so much used. Ketches had two masts, both square-rigged; the mainma.st, very much higher than tlie after-mast, was placed very nearly in the centre of the vessel, and the great spread of after-canvas was balanced by large and numerous- fore and aft sails forward. The ketch was at one time a favorite yachting rig, and was also nuicli used for bomb-vessels, the clear forward deck being most convenient for mounting a mortar. KETCH, Jack. The popular name for a pub- lic hangman, derived from .John Ketch, an Eng- lish executioner notorious in the sevent<>enth cen- tury. The name is also referred to .Jacquet, a former holder of the manor of Tyburn. KETEL, ka'td, Cornelis (1548-1610). A Dutch painter, born at Gouda. He was a pupil for a very short time of Anlhonie van Montfort at Delft, and then went to Paris and worked at FontainebleaiL Afterwards he went to England ( 157.T ) , and painted a nund)er of portraits at the Court. In 1581 he settled at Amsterdam, where his principal work, a "Banquet of Marksmen" (15881. is preserved in the Ryk,s-museum. KE'TONES (apocopated from arrtoiw, from acet-ic, from Lat. accliim, vinegar), or .ceto.nes. A large and important class of carbon compounds that are in many respects similar to the alde- hydes. While the aldehydes (q.v. ) are character- ized by the carbonyl group CO to which one hydrogen atom and some hydrocarbon radicle are attached, and while most organic aci<ls are char- acterized by the carbonyl group CO to which one hydroxyl group (OH) and some hydrocarbon radicle are attached — the ketones contain a car- bonyl grou]) to which tiro hydrocarbon radicles are attached. If R stand for anv livdrocarhon radicle, like methyl (CH,), or ethyl (C;H,), the following fornuilas represent respectively the structure of any aldehyde, any organic acid, and anv ketone: H I CO OH I CO R CO I I I R R R An nliieliyde .
acid A ketone
For example: Ordinary aldehyde, acetic acid, and acetone (the simplest ketone) are represented respectively by the following structural formulas: H " OH CH, I I I CO CO CO CH, Ordinary aldehyde CH, Acetic acid CH, Acetone (a ketone) .Tust as aldehydes are obtained from primary alcohols by oxidation, so are ketones produced by the oxidation of secondary alcohols. (See Alcohols.) In cither case the oxidation consists in the removal of two hydrogen atoms from the alcohol molecule. Thus normal propvl alcohol, CH,.CH..CH:OH. yields CH,.CIL.CH6 (propio- nic aldehyde), while iso-propyl alcohol, CH,.
