204 Intellisrence and Miscellanies. 



"a 



" The other spot alluded to, is called Stipsy by the inhab- 

 itants. It is near the centre of the island, and was well 

 known to the ancients, being spoken of by Pliny, as afford- 

 ing an alum, held next in estimation to that procured from 

 Egypt. This is a cave also, and at the bottom of a hill. Its 

 entrance is low and narrow, but it forms a chamber one hun- 

 dred and twenty feet in length. Its atmosphere preserves a 

 heat of 90", and in some places of 100° Fah. The rock 

 forming the roof and sides is of a pasty consistence, and 

 every where inflated into oval cells often a foot in length. 

 It is in these cells that we find the alum, which lines them 

 all around with the most delicate incrustations or frost work. 

 Towards the entrance of the cave occur masses of branchy 

 gypsum, and within delicate acicular crystals of the same 

 substance." 



As soon as I saw the Milo alum, I was struck with its 

 want of similarity in appearance to the specimens of Eng- 

 lish and Scotch alum which I had seen in cabinets, and I 

 was immediately led to think of the native soda alum of 

 South i\merica, recently analyzed and made known by Dr. 

 Thomson.* I accordingly made use of the following pro- 

 cess, to render my conjecture concerning its nature, certain. 



A portion of it was dissolved in water, to which was ad- 

 ded in excess, carbonate of ammonia, to precipitate the alu- 

 mine and other earths, as well as any metallic oxides which 

 might be present. The residual liquid was evaporated to 

 dryness and heated to redness in a platina crucible to dissi- 

 pate the ammoniacal salts. The residue was dissolved in 

 water, in which it proved highly soluble. By its taste it was 

 recognized to be sulphate of soda. The solution was set 

 aside for spontaneous evaporation. It shot into short pris- 

 matic crystals, which on being slightly heated underwent 

 the watery fusion. In the course of a few days, the entire 

 mass became covered with a white efflorescence. There- 

 fore, there can remain no reasonable doubt concerning the 

 nature of the substance in question. 



The specimen examined was from the cave first mention- 

 ed, between which and the specimens from the other, there 

 is a slight difference in appearance ; they are both however 

 the same in all important respects. The former consists of 

 parallel straight fibres not very closely aggregated, from one 



* Annals of the Lyceum of Natural History of New York, Vol. Ill, p. 19. 



