498 BORATES. 



to heat as a preparatory operation, to burn off the oily or fatty matter 

 which surrounds it. Formerly the manufacture was confined to 

 Holland, and it seems not to have been known that an addition of 

 soda was necessary to saturate the boracic acid. 



Borax is now abundantly manufactured in France, by the combi- 

 nation of the boracic acid, obtained from Tuscany, with soda; the 

 French consume, annually, about 25 tons, and they no longer import 

 the tincal. 



In forming borax in France, they dissolve 1200 Ibs. of carbonate 

 of soda in 1000 Ibs. of water, and add, by 20 Ibs. at a time, 600 Ibs. 

 of Tuscan boracic acid ; the processes are conducted in leaden boil- 

 ers, by repeated solutions and crystallizations, and many circumstan- 

 ces must be attended to in order to obtain large and handsome crys- 

 tals. 100 Ibs. of the best Tuscan boracic acid, containing about 

 half its weight of the pure acid, produce about 150 of refined bo- 

 rax ; but as the acid is not always pure and there is some loss in the 

 processes, the product is ordinarily not more than 140 or 142 Ibs. of 

 borax from 100 of boracic acid.* 



5. USES. Formerly used internally as a sedative, and still employ- 

 ed to form a gargle to remove the aphthous crust from the mouths of 

 children ; it is a flux for the blowpipe ; for the vitreous materials of 

 artificial gems or pastes, and for the glazing of porcelain. Known 

 from remote antiquity, and it is mentioned by Pliny as chrysocolla or 

 gold glue, in allusion to its use in soldering the precious metals ; 

 from which it removes impurities, preventing also oxidation. 



BORATE OF AMMONIA. 



1. PROCESS. By digesting boracic acid with ammonia, we obtain 

 small rhomboidal octahedra. 



2. PROPERTIES. 



(a.) Taste sharp ; turns the blue vegetable test liquors green ; 

 undergo slight efflorescence in the air. 



(b.) The ammonia is expelled by heat and the boracic acid is left; 

 according to Lassone,f the entire salt melts into a grayish glass, and 

 gives after solution, the same crystals as before. 



(c.) Decomposed by the fixed alkalies both in the moist and dry 

 way, 



BORATE OF BARYTA. 



Add boracic acid to barytic water, and a white, insipid, insoluble 

 powder precipitates. 



BORATE OF STRONT1A. 



1. Same mode of formation ; a copious precipitate. 



2. Prone to an excess of base; soluble in 130 parts of boiling 

 \vater, and is scarcely affected by cold water. 



* Gray's Op. Chem. p. 526. t Aikin, Vol. I, p. 156. 



