512 FLUATES. 



fluates are generally used for this purpose, especially the fluate of 

 ammonia. 



(b.) Soluble in fluoric acid, and in the nitric and muriatic. 



(c.) The native fluate is phosphorescent on hot iron. 



(d.) Insipid not affected by air at 51 W. fuses into a trans- 

 parent glass. 



(e.) Decomposed by sulphuric acid, with evolution of fluoric acid 

 gas, as already stated. 



NATURAL HISTORY. This belongs to mineralogy, and the uses 

 of the mineral to the arts ; but it may be briefly stated here, that 

 hitherto only one mine has been discovered that affords the massive 

 fluor, in pieces of sufficient size and firmness to admit of their be- 

 ing wrought. This mine it at Castleton, in Derbyshire, England, 

 and is called the spar rnine.J I saw it in 1805, when it was far 

 from being exhausted. 



FLUATE OF MAGNESIA. 



1. PREPARATION. 



(a.) Carbonate of the earth and liquid fluoric acid, with a mild 

 heat ; there is effervescence ; near saturation, the salt falls down 

 chiefly in a gelatinous precipitate, probably mixed with silica. 



(b.) Soluble salts of magnesia, mingled with liquid fluoric acid 

 or with solutions of alkaline fluates. 



2. PROPERTIES. Scarcely soluble in water ; rather more so in 

 alcohol ; not decomposed by heat, nor by any acid, but soluble in the 

 strong acids. 



The Brucite, or Condrodrite contains a native fluate of magnesia. 



FLUATE OF ALUMINA. 



1. PROCESS. 



Sa.) The earth precipitated from alum is soluble in fluoric acid. 

 b.) Alum and alkaline fluates decompose each other, and pro- 

 duce fluate of alumina, and sulphate of alkali. 



2. PROPERTIES. 



(a.) The pulverulent compound becomes gelatinous by evapora- 

 tion, but does not crystallize. 



} In that mine, it is not, as every where else, mixed with other spars, and with 

 metallic matters, but constitutes entire veins by itself; these veins lie imbedded in 

 solid limestone, and are wrought for the sake of the fluate of lime only, which is 

 manufactured into articles of furniture, as candle sticks, salt-cellars, ink stands, &c., 

 and into the most beautiful ornaments for houses and palaces, as urns, vases, pyra- 

 mids. 



In this mine, attached to the walls and roofs, are the most beautiful crystallized 

 incrustations, and regular stalactites of carbonate of lime, some of which last have 

 reached the floor, and form continued pillars, and as they, and the incrustations are 

 generally of a snowy whiteness, they present a very brilliant spectacle when those 

 dark regions are lighted up with candles. 



