9 



Muriate of Ammonia, as already stated, afforded, on evaporation, a 

 brown powder, which consisted of Alumine 1 gr. C^b) and oxide 



of Iron 0.25 grs. 



The mineral was also heated with Nitrate of Barytes, in order 

 to confirm the inference deduced as to the quantity of potash in- 

 dicated by the Alum crystals in the first process with Sulphuric 

 Acid, Fifty grains of it, in fine powder, were mixed with 250 grs. 

 of powdered Nitrate of Barytes, and heated to redness in a platina 

 crucible, during more than half an hour. To the fused mass, on 

 cooling, diluted muriatic acid was added, which dissolved a part 

 only. The residuum was therefore again treated with 150 grams 

 of Nitrate of Barytes, and the product of this operation dissolved in 

 muriatic acid. The filtered liquor was then decomposed by means 

 of subcarbonate of Ammonia. The fluid was separated by the 

 filter, evaporated to dryness, and the muriate of Ammonia expelled 

 by heat. The dry mass lixiviated with water, and again evapo- 

 rated, yielded a residuum which had all the characters of nninate 

 of Po'tash, and when dry weighed 3.50 grs. equivalent to 2.22 grs. 

 of potash, consequently for 100 grs. of the mineral 4.44 of potash. 



If we adopt the results of the first process, adding the quantity 

 of AJumine afforded by the second, we shall approximate to the 

 constituents of this mineral, and their respective quantities, with suf- 

 ficient accuracy for the purposes of scientific arrangement. 



VOL. XIII. <*! 



