66 



GLAUBERITE, A KEW MINCKAt. 



•f water. 



Hardness. Their hardness exceeds that of sulphate of lime, but rs iit=* 



ferior to that of carbonate of lime. 



Action of fire. Exposed to the fire, the glauberite splits, decrepitates, 

 and melts into a white enamel. 



Singular action Immersed in water, its surface becomes of a milky white, 

 and in a little time the whole of the crystal grows com- 

 pletely white and opake. Taken out of the water and 

 dried, it does not resume its transparency, but the white 

 coating- falls to powder ; and, if it be entirely removed, the 

 nucleus is discovered remaining unaltered. It is the only 

 mineral substance that possesses this property. 

 The specific gravity of the glauberite is 2*73« 

 This salt, the crystals of which at first sight bear some 

 resemblance to those of axinite, and the fragments of which 

 are a little like those of sulphate of lime, differs essentially 

 from the latter, whether anhydrous or possessing its water 

 of crystallization, in its primitive form,, and in the second* 

 ary forms derived from it. 



It is composed of anhydrous sulphate of lime •»•• 40 

 anhydrous sulphate of soda •••• 51 



Spec. gra*. 



Crystals re- 

 sembling it. 



Its component 



ports. 



100 



No water. Mr. Brongniart satisfied himself, that ft contained no 



water, not only by several calcinations at the temperature 

 nearly of melting silver, but also by distilling it after Mr. 

 Berthollet's manner with iron filings, when he could obtain 



Sulphate of 

 soda, 



and of lime. 



No loss. 



He ascertained the presence of the sulphate of soda by- 

 solution and crystallization, which afforded him well de« 

 fined crystals of this sulphate. 



The sulphate of lime he found by decomposing this 

 salt both by carbonate of ammonia and oxalate of ammo* 

 nia. 



As he had no loss, but what cannot be avoided in che« 

 mical operations conducted with the greatest care, and thife 

 loss did not amount to one per cent, he presumes, that this 

 stone contains no other ponderable matter essential to it 

 but the two salts mentioned above : and to be more certain 

 of this, he examined carefully, whether it contained no 



phof-pha*eB S 



