BIJOUTEY 341 



ncetate of potash, by no means tho whole of the carbonic acid is expelled, and a point 

 is arrived at when a considerable quantity of crystals is deposited ; they consist of 

 very pure bicarbonate of potash. In making acetate of potash on tho largo scale, tho 

 quantity of crystalline precipitate obtained in this manner is sometimes very large. 

 Bicarbonate of potash is usually tolerably pure. If -well crystallised, all the im- 

 purities remain in the mother-liquor, and on heating to redness almost exactly the 

 theoretical amount of residue is left, viz. 69 '05 per cent. Crystallised bicarbonate 

 of potash always contains one atom of water, its formula being KO, 2C0 2 + HO 

 (XBOO*). 



Bicarbonate of Soda. This salt is obtained by the same methods as the salt of 

 potash. Tho crystals have a corresponding formula to the potash salt ; namely, NaO, 

 2C0 2 + HO (WaHCO 3 ). It requires about 13 parts of water at 60 to dissolve it. 

 When pure, 100 parts leave 63-18 of NaO.CO 2 (Xa 2 CO 3 ), on ignition. 



The bicarbonates of potash and soda lose carbonic acid by the boiling of an aqueous 

 solution. 



Many chemists regard carbonic acid as being bibasic, the true formula being C 2 4 , 

 instead of CO 2 . This view is probably the correct one, and it explains why tho bicar- 

 bonates are neutral instead of acid salts. Moreover, C 2 4 corresponds to 4 volumes, 

 like organic substances generally ; whereas, if wo assume CO 2 as one atom of the gas, 

 we are complied to admit a 2-volume formula. This view has, however, been con- 

 siderably modified by our modern theoretical chemists. 



BICE. A light blue colour prepared from smalt. There is a green bice prepared 

 by mixing some yellow orpiment with smalt. 



BXDERT. An Indian alloy of considerable interest, named Bidery, from Bider, a 

 city N.E. of Hyderabad. Many articles are made, remarkable for elegance of form 

 and for gracefully-engraved patterns. Although the groundwork of this composition 

 appears of a blackish colour, its natural tint is that of pewter or zinc. 



Dr. Heyne says it is composed of, copper, 16 ; lead, 4 ; tin, 2 ; and to every 3 ounces 

 of alloy 16 ounces of spelter (that is, of zinc) are added, when the alloy is melted for 

 use. To give the esteemed black colour and to bring out the pattern, it is dipped in 

 a solution of sal-ammoniac, saltpetre, common salt, and blue vitriol. Dr. Hamilton 

 saw, zinc, 12,360 grains, copper 400, and lead 414, melted together under a mixture 

 of resin and bees'-wax, introduced into the crucible to prevent calcination ; it was then 

 poured into moulds of baked clay, and the articles handed over to be turned in a lathe. 

 Though called bidery and sometimes vidry, it is manufactured in other places. In 

 some parts of the Nizam's dominions, specimens wore obtained, for the Exhibition of 

 1851, of great beauty. Bidery does not rust, yields little to the hammer, and breaks 

 only when violently beaten. According to Dr. Hamilton, bidery is not nearly so 

 fusible as zinc or tin, but melts more easily than copper. Dr. Roylc, Lecture on the 

 Great Exhibition of 1851. 



BIJOTTTRY. (Bijouterie, Fr.) Jewellery ; the manufacture of and dealing in 

 jewellery. This work is not tho place in which to describe the almost endless variety 

 of articles which come under this denomination. The principal place for the manu- 

 facture, in England, is Birmingham, but formerly the trade was largely carried on in 

 Derby, Edinburgh, and London. During the last twenty-five years the jewellery trado 

 of Birmingham has made rapid progress. It has been estimated that the value of the 

 gold annually consumed in the jewellery and gilt-toy trade of that town amounts to 

 between 600,00<M. and 700,0002., and of the silver to from 100,0002. to 150,0002., 

 whilst tho precious stones and their imitations have been valued at a quarter of a 

 million sterling. (See papers by Mr. J. S. "Wright in ' The Resources, Products, and 

 Industrial History of Birmingham,' 1866 ; and by Mr. "W. G. Larkins in ' Journal of 

 tho Society of Arts,' March 1, 1872.) 



The trade in jewellery forms one of tho most important branches of French com- 

 merce ; on which a French writer says : ' La bijouterie est uno des branches les plus 

 importantos du commerce Fran$ais, et c'est cllo quo constate, de la maniere la plus 

 evidcnto, notre superiorite dans les arts du dessin et les progres toujours croissans 

 de 1'industrie Pansienno. Dans cette partio essentielle, elle n'a pas de rivaux, et elle 

 rend tributaire do notre pays presque touto 1'Europo et uno grande partie de 1'Asie et 

 de I'Am^rique.' Of late years, however, the Parisian trado has been declining ; but 

 French jewellery has still so high a reputation that English manufacturers often find 

 it to their interest to affix French labels to their goods. A quantity of cheap jewellery 

 is also imported from Germany. See AGATE. 



Tho ordinary practice has been to divide articles of this character into two prin- 

 cipal kinds fine jewellery and false jewellery (bijouticr en fin and bijoutier en faux). 

 Another division, among the French jewellers especially, has been to adopt four 

 classes: 1, fine jewellery, which is all gold; 2, silver jewellery; 3, false jewellery; 

 and, 4, jewellery of steel or iron. 



