1822.] Scientific Intelligence. 467 



An analysis was made expressly for the purpose of ascertaining whe- 

 ther lime existed in the mineral, and in that case, the fluoric acid, 

 perhaps, might be combined with it, as Vauquelin supposes ; but not a 

 trace of lime was found. 



In a comparative analysis of the lepidolite from Utoen, there was 

 found 1*482 per cent, of fluoric acid, and 0*7508 of phosphoric acid, 

 and the mineral appeared to be mixed with quartz, upon which the 

 greater hardness depends. 



Ros had discovered fluoric acid in the white mica, and MM. Gme- 

 lin and Winz found, in mica from Braddbo, near Fahlun, in Sweden, 

 1*9512 per cent, fluoric acid, but no phosphoric acid. 



Sulphate of lithia from the lepidolite, according to an analysis by 

 acetate of barytes, consisted of 



Per cent. 



Sulphuric acid 72*52 



Lithia 27*48 



10000 

 According to an analysis by means of acetate of lead : 



Per cent. 



Sulphuric acid 71 '60 



Lithia 28*40 



100*00 



It appeared, therefore, highly probable, that Arfwedson and Gmelin 

 had overlooked another substance in the alkali of the petalite. In 

 repeating the analysis of petalite, Dr. Gmelin obtained soda. 



Arfwedson found sulphate of lithia composed of 



Sulphuric acid 68*65 



Lithia 31*35 



VI. Dr. Gmelin on the Tourmaline from Karingshrakka, in Sweden. 



When Dr. Gmelin was at Stockholm in 1816, he analyzed the tour- 

 maline from Karingsbrakka, but had a loss of more than 10 per cent. 

 At that time he could not find boracic acid, though he had directed 

 liis attention to it. The great loss made him afterwards repeat his 

 analysis ; but still he had a considerable deficiency, though not so 

 great as formerly. He heated the powdered tourmaline in the usual 

 way with carbonate of barytes, dissolved in muriatic acid, and obtained 

 silica in the ordinary mode. 



He threw down all barytes from the solution by sulphuric acid, neu- 

 tralized the excess of acid afterwards with pure ammonia, and precipi- 

 tated the iron and alumina by carbonate of ammonia, and separated 

 these two substances from each other by potash. 



The magnesia remained as a triple salt in the solution, which now 

 was evaporated to dryness, and heated red-hot, dissolved again in 

 water, when a small quantity of silica remained. The Hquid was then 

 decomposed by acetate of barytes, filtered, evaporated, and the salt 

 heated. The dry mass was washed with water to dissolve the alkaline 



2h2 



