^/ 



231 



paca, in Peru, where it had been found in the nitrate of soda 

 beds. From the analysis of this chemist it seemed to be com- 

 posed of water, limCj and boracic acid, and he called it hydro- 

 boro-calcite. tJlex, however, examined a specimen from the 

 same locality, and finding it mixed with the nitrate and sulphate 

 of soda, he boiled the whole with water for the extraction of 

 these, and, analyzing the residue, he expressed his results in this 



formula, ^^^ ^BO 3 +2CaO 3B0 3 + lOHO, 



and he named the mineral Natro-boro-calcite. Professor Ander- 

 son, of Glasgow, afterwards analyzed a specimen from the same 

 locality, which, though somewhat mixed with foreign matter, he 

 shewed to consist essentially of the mineral of Ulex. A few ob- 

 servations extracted from the paper containing these results,"^ 

 will sufficiently mark the characters of the Peruvian mineral, 



and what is known of the geological nature of its till now unique 

 locality. 



"The Natro-boro-calcite is found in the nitrate of soda beds of 

 the province of Tarapaca, in Peru, and is known to the natives 

 by the name of Tiza. It occurs in rounded masses, varying from, 

 the size of a hazel-nut to that of an egg. Externally these have 

 a dull and dirty appearance ; but when broken across they are 

 found to be formed of a series of interlaced needles of a brilHant 

 white color, and silky lustre. These crystals were extremely 

 minute in all the pieces I examined, but the specimen analyzed 

 by Hayes Avas composed of prisms a quarter of an inch in length. 



*^The qualitative analysis indicatecl the presence of boracic and 

 sulphuric acids, lime, soda, water, siliceous sand, and traces of 

 chlorine, Ulex found also traces of nitric acid, but that which I 



examined contained none. 



/' The quantitative analysis gave results according very closely 

 with those' of Ulex, excepting that previous to his analysis he 

 boiled the mineral with water, to extract the nitrate and sulphate 

 of soda which he had detected, and which are obviously a me- 

 chanical admixture. This was not done in my case, as the 

 analysis was made for commercial purposes and I was desirous 

 of ascertaining its exact composition as it occurs. Ulex obtained : 



Calc. 



25-60 

 15-93 



8-82 

 49-64 



lOO'O 100-00 



wliich numbers agree very well with the formula, 



NaO 2BO3 +20aO BBO3 +10HO. 



* Proc. Phil Soc. Glasgow, Feb, 1863. 





Expt. 



Water, 



26-0 



Lime, 



157 



Soda, 



8-8 



Boracic acid, 



m 



40-5 



