ACCOUNT OF A MINERAL SUBSTANCE. 13,1 



The acid appeared to have acted but flightly upon the pow^ 

 tier ; as the former remained colourlefs, and the latter did not 

 feem to be diminiflied. A portion, however, chiefly of iron, 

 was found to be diflblved ; for ammonia formed a yellow floc- 

 culent precipitate ; prufliate of potafli produced one which 

 was blue ; and tincture of galls, when the excefs of acid had 

 been previoufly faturated by an alkali, formed a precipitate of 

 a rich purplilh brown colour. 



Experiment 2. 



Another portion of the powder was, in like manner, digefted In nitric acid.: 

 with nitric acid ; but, excepting fome flight traces of iron, '" e aftlon * 

 this acid afforded nothing worthy of notice ; the action of it 

 upon the ore, was indeed fcarcely perceptible. 



Experiment 3. 



Some of the pulverized ore was digefted with concentrated In fulphuric 

 fulphuric acid, in, a ftrongly-heated fand-bath, until nearly the * c ' , „. 

 whole of the acid was evaporated ; the edges of the mafs then 

 appeared blueifli, and became white, when boiling diftilled 

 Water was added. 



This acid certainly acted much more powerfully than thofe 

 which have been mentioned ; but ftill only a fmall part of the 

 ore was diflblved. It muft however be obferved, that a very 

 copious blue precipitate was obtained by prufliate of potafli ; a 

 plentiful purplilh brown precipitate was alfo produced by tine-" 

 ture of galls, after the excefs of acid had been faturated by an 

 alkali; and, laftly, when the yellow ferruginous precipitate 

 formed by ammonia was diflblved in diluted nitric acid, fome 

 white flocculi remained, which were completely infoluble in 

 the acid, even when it was added fo as to be in considerable 

 excefs. 



From thefe experiments it was evident, that the ore could 

 lot readily be decompofed by the direct application of the 

 lineral acids ; and I therefore had recourfe to the following 

 tethod, which has frequently been employed with fuccefs in 

 imilar cafes. 



ANALYSIS. 

 A. 

 A mixture of 200 grains of the powdered ore with five times Fufion with car- 

 le weight of carbonate of potafli, was expofed to a ftrong red ^nate of potafh. 



K 2 heat, 



