428 M. Stromeyer on Polyhalite. [Dec. 



was of opinion that it ought to be classed among the anhydrites, 

 and assigned to it the specific name of fibrous anhydrite, it being 

 principally distinguished from the other varieties of this fossil by 

 its fibrous texture ; which opinion was afterwards adopted by the 

 celebrated Mohs, Karsten, and many other intelligent mineralo- 

 gists. 



Besides having received from him many other Austrian and 

 Hungarian fossils, I am indebted for a specimen of this mineral 

 to the kindness and politeness of the celebrated M. Schreibers, 

 Director of the Imperial Cabinet of Natural History at Vienna, 

 and one of the friends and correspondents of our own society. 

 This specimen I have subjected to a chemical examination, no 

 analysis having hitherto been made of the fibrous anhydrite. 



My first experiments upon this mineral excited many doubts as 

 to its identity with anhydrite, and led me to conjecture that its 

 composition was entirely dift'erent from that usual to anhydrite, 

 so much so that they ought by no means to be referred to one 

 and the same species. 



The principal respect in which our fossil differs from the anhy- 

 drite is, that apphed to the tongue it produces a sense of a slight 

 saltness and bitterness, which can by wo means be attributed to 

 any admixture of rock salt, generally detected in anhydrite, 

 because its solution, whether in water or nitric acid, is scarcely 

 affected by the presence of nitrate of silver. 



It is to be observed too, that anhydrite is much more easily 

 acted on by water, and that it is dissolved with hardly any 

 assistance from heat, depositing sulphate of lime, and producing 

 a saline bitter solution, which, in addition to the sulphate of 

 lime, exhibits also, after evaporation, many other crystals of some 

 other sulphate prismatically shaped, and possessing the same 

 flavour as the fossil itself. But the greatest difference between 

 this and anhydrite is that, when exposed to the fiame of spirits 

 of wine, it immediately melts, and is very easily reduced to an 

 opaque lump. 



These circumstances have induced me to suspect that this 

 mineral agrees with, or at least is very nearly related to, that 

 which was many years since discovered at Villaruba, near 

 Oceana, in Spain, ^' here it was also found in strata of rock salt, 

 and named giauberite by Brongniart, (to whose experiments we 

 are indebted for our knowledge of it), it being found to consist 

 of anhydrous sulphate of hme and sulphate of soda. 



And although I have myself never met with giauberite, nor 

 have been able to judge of it, except from the description and 

 chemical analysis of it given by Brongniart in the Journal des 

 Mines,* I was nevertheless inclmed to consider this opinion ex- 

 tremely probable, as well on account of the greater solubility of this 

 by means of water and acids, and the saltness and bitterness of its 



* Memoir sur une Nouvelle Espece de Mineral do la Classe lies Sels nomm^e 

 Glaoberite, par Alex. Brengniart, vol. xxiii. p. 5—80. 



