206 Elements tf Mineralogy. 



of water, but of the mineral alkali only about 

 5 parts are really faturated, the reft is unfa- 

 turated ; and hence in many cafes borax ads 

 as an alkali. 



Borax comes to Europe from the Eqft 

 Indies in a very impure ftate in the form of 

 large, flat hexangular or irregular cryftals, 

 of a dull white or greenifh colour, greafy to 

 the touch, or in fmall cryftals, as it were ce- 

 mented together by a rancid, yellowifh, oily 

 fubftance, intermixed with marl, gravel, and 

 other impurities. In this ftate it is called 

 brute borax, chryfocolla or tincah 



It is purified by folution, filtration and 

 cryftalifation ; and the cryftals thus obtained 

 are calcined to free them ftill further from 

 greafinefs, and then diflblved, filtered, and 

 cryftalized a 2d time ; fometimes more mi- 

 neral alkali is added, as it is faid that tincal 

 contains an excefs of fedative fait. 



It has been long thought that borax was a 

 factitious fubftance, but it is now beyond all 

 doubt that it is a natural production, fince 

 Mr. Grill Abrahanifon fent fome to Sweden in 

 the year 1772 in a cryftaline form as dug out 

 of the earth in the kingdom of Thebet,v?here 

 it is called pounxa, my poun and houipoun* 

 as borax is purified alfo in the Eajl Indies, Mr. 



Engejlrom 



