758 CHAMELEON, MINERAL 



CHAXiCOIiXTZ:. A name applied to cogper-uranite or torberite, a hydrated 

 phosphate of uranium and copper. 



CH ALCOPHYXiXtXTE. A hydrated arsenate of copper, known also as tamarite 

 and copper-mica, the crystals being easily separated into laminae, like mica. 



CHALCOPYRITE. A mineralogical name for copper-pyrites. See COPPER. 



CHAXiCOSXNE. A synonym of copper-glance. See COPPER. 



CBAXiCOSTXBZTE. A sulphide of antimony and copper, from Wolfgborg in 

 the Hartz. 



CHAIiCOTRICHITE. A name applied to the hair-like forms of red oxide of 

 copper, known commonly as plush copper-ore. 



CHAXiX. (Craie, Fr. ; Kreide, Ger.) An earthy carbonate of lime, white, 

 opaque, soft, dull, or without any appearance of polish in its fracture. Its specific 

 gravity varies from 2'4 to 2'6. 



The following analysis, by Mr. W. J. Ward, shows the composition of a sample of 

 chalk from near Gravesend (after having been dried at 212 F.): carbonate of lime, 

 98'52; carbonate of magnesia, 0'29; sulphate of lime, - 14; peroxide of manganese, 

 0'04 ; phosphoric acid and organic matter, traces ; ignited insoluble residue, chiefly 

 silica, 0-65. 



When purified, chalk is called whiting and Spanish white, in England ; Schlemm- 

 Jcreide, in Germany ; blanc de Troyes, and blanc de Meudon, in France. Pure chalk 

 should dissolve readily in dilute muriatic acid, and the solution should afford no 

 precipitate with water of ammonia. Chalk is burnt into lime in great quantities, in 

 which state it is used as a manure, and for making mortar and whitewash. Some of the 

 lower beds, which are argillaceous, afibrd a good hydraulic cement, equal in every 

 respect to Roman cement. 



Of late years, it has become the custom to manure land with unburnt chalk spread 

 on the surface in the proportion of about 40 loads (tons) to an acre. The effect pro- 

 duced by chalk applied in its crude state is similar to that resulting from the applica- 

 tion of quicklime, but more lasting, on some lands not requiring to be renewed for 

 several years : it also has the advantage of rendering the soil mechanically lighter, 

 from the larger quantity in which it is used. 



In certain districts, chalk is sometimes used as a building material. 



CHAIiK, BXiACX. An indurated clay, containing much carbon. The finer 

 kinds are used for drawing on paper. 



CHAX<X, FRENCH. Steatite, or soap stone : a soft magnesian mineral. 



CHAXiX, RED. A clay coloured with the peroxide of iron, of which it contains 

 about 17 per cent. Also a ferruginous carbonate of lime. 



CHAXiXiIS. About the year 1832 this article was introduced, and was certainly an 

 elegant silk and worsted fabric. It was made on a similar principle to the Norwich 

 crape, only thinner and softer, composed of much finer materials ; and instead of a 

 glossy surface, as in Norwich crapes, the object was to produce it without gloss, and 

 very pliable and clothy. The best quality of challis, when finished with designs and 

 figures (either produced in the loom or printed), commanded the attention of the 

 higher circles, and became a favourite article of apparel at their fashionable resorts 

 and parties for several years. The worsted yarn for the weft of this article was spun 

 at Bradford, from numbers 52's to 64's. The making of the challis fabric soon after- 

 wards commenced in the North, but it has given way to the ever-varying caprices of 

 fashion. 



CHALYBEATE is a name given in medicine to preparations of iron. 



CHAIiYBITE. A synonym of carbonate of iron, or spathose iron-ore. See 

 IKON. 



CHAMELEON, lYXINERAIi. As this compound so long known in chemistry 

 as a mere curiosity, on account of the surprising changes of colour which it spon- 

 taneously assumed has of late been largely employed for whitening tallow, palm-oil, 

 and decolouring other organic matters, it merits description in this Dictionary. It 

 exists in two states : one of which is called by chemists the manganate of potash, and 

 the other the permanganate ; denoting that the first is a compound of manganic acid 

 with potash, and that the second is a compound of permanganic acid with the same 

 base. They are both prepared in nearly the same way : the former by calcining 

 together, at a red-heat in a covered crucible, a mixture of one part of the black per- 

 oxide of manganese with three parts of the hydrate of potash (the fused potash of the 

 apothecary). The mass is of a green colour when cold. It is to bo dissolved in cold 

 water, and the solution allowed to settle, and become clear, but by no means filtered, 

 for fear of the decomposition to which it is very prone. When the decanted liquid is 

 evaporated under the exhausted receiver of an air-pump, over a surface of sulphuric 

 acid, it affords crystals of a beautiful green colour, which should bo laid on a clean 

 porous brick to drain and dry. They may be preserved in dry air, but should be 



