CHA 



CHA 



porous sand-stone is scarcely so deficient 

 in springs of water, and yet, except upon 

 akqost perpendicular descents, the white 

 surface of the chalk is uniformly covered 

 with fine turf or wood. 



The chalk hills in England occupy a 

 greater extent than in any other country ; 

 they run in a direction nearly from east 

 to west, parallel to each other, and sepa- 

 rated by ranges of sand-stone, and low 

 tracts of gravel and clay. The most north- 

 ern and loftiest range of chalk com- 

 mences at the promontory of Flambo- 

 rough-head, in Yorkshire, and proceeds 

 westward for nearly twenty miles. In the 

 county of Lincoln are some fragments of 

 a ridge near Grantham. Two ridges tra- 

 verse the midland countries, and reach as 

 far west as the borders of Oxfordshire : 

 these ridges are no where so conspicuous 

 as in the county of Bedford, where they 

 approach near to each other, being only 

 separated by the Woburn and Ampthill 

 range of sand-stone. The country south 

 f the Thames also contains two ridges, 

 the one commencing at the North and 

 South Foreland, passing through the 

 north of Kent, the middle of Surry, and 

 the north of Hampshire, and including 

 the North Downs of Banstead, Epsom, 

 Sec. : the other, commencing near Mast- 

 ings and at the lofty promontory of 

 Beachy-head, passes through Sussex and 

 the south of Hampshire, into Dorsetshire, 

 including the South Downs. The north 

 part of Frajice also abounds in chalk: 

 it is besides met with in some of the 

 Danish islands in the Baltic, and in Po- 

 land. 



The uses of chalk are very extensive : 

 the more compact kinds are used as 

 building stone, and are burnt to lime 

 (nearly all the buildings in London being 

 cemented with chalk-mortar :) it is also 

 largely employed in the polishing of me- 

 tals and glass]! in constructing moulds to 

 cast metal in, by carpenters and others as 

 a material to mark with, and by starch- 

 makers and chemists to dry precipitates 

 on, for which it is peculiarly qualified, on 

 account of the remarkable facility with 

 which it absorbs water. 



CHALK stones. It is well known that 

 concretions occasionally make their ap- 

 pearance in joints long subject to gout. 

 These concretions, from their colour and 

 softness, have received the name of 

 chalk-stones. They are usually small, 

 though they have been observed of the 

 size of an egg-. It had long been the 

 opinion of physicians, that these concre- 

 tions were similar to the urinary caknli. 

 See CALCULT. 



Of course, after the discovery of uric 

 acid by Scheele, it was usual to consider 

 the gouty chalk-stones as collections of 

 that acid. They were subjected to 

 chemical analysis by Dr. Wollaston in 

 1797, who found them composed of uric 

 acid and soda. Gouty concretions are 

 soft and friable. Cold water has little ef- 

 fect upon them ; but boiling water dis- 

 solves a small portion. If an acid be add- 

 ed to this solution, small crystals of uric 

 acid are deposited on the sides of the 

 vessel. These concretions are complete- 

 ly soluble in potash, when the action of 

 the alkaline solution is assisted by heat. 

 When treated with diluted sulphuric or 

 with muriatic acid, the soda is separated ; 

 but the uric acid remains, and may be se- 

 parated by filtration. The liquid, when 

 evaporated, yields crystals of sulphate or 

 muriate of soda, according to the acid 

 employed. The residuum possesses al^ 

 the characters of uric acid. 



When uric acid, soda, and a little warm 

 water, are triturated together, a mass is 

 formed, which, after the surplus of soda 

 is washed off, possesses the chemical pro- 

 perties of gouty concretions. 



CHALLENGE, in law, is an exception 

 made to jurors, who are returned to a 

 person on a trial. 



This challenge is made either to the 

 array, or to the polls : to the array, when 

 exception is taken to the whole number 1 

 of jurors impannelled ; and to the pol|s, 

 when an exception is made to one OR 

 more of the jury as not indifferent. 



Challenge to the jurors is likewise di- 

 vided into challenge principal or pe- 

 remptory, and challenge for cause ; that 

 is, upon cause or reason alledged. Chal- 

 lenge principal, is what the law allows 

 without any cause alledged, or further ex- 

 amination : as, a prisoner arraigned at the 

 bar for felony may challenge peremptori- 

 ly the number allowed him by law, be- 

 ing twent)', one after another, alleging 

 no further cause than his own dislike : 

 and the jurors, so challenged, shall be 

 put off, and new ones taken in their 

 places. 



In cases of treason, the number of thir- 

 ty-five jurors may be peremptorily dial 

 lenged, without shewing any cause : and 

 more, both in treason and felony, may be 

 challenged, shewing cause. 



If those who prosecute for the king, 

 challenge a juror, they- are to assign the 

 cause ; and if the cause alleged be not a 

 good one, the inquest shall be taken. 

 When the king is party, if the other side 

 challenge any juror above the number 

 allowed, he ought to show cause of his 



