-v/4 Professor Gmelin's Analysis of Helvine* 



Experiments Jbr ascertaining the Existence of Fluoric 

 Acid in Helvine. — a, 1.605 grains of powdered helvine were 

 mixed with three times their weight of carbonate of soda and 

 ignited. A black fused mass was obtained, showing on the 

 edges a reddish-yellow hue. Water, when digested with this 

 mass, was not coloured, nor did it receive any smell ; a quite 

 colourless liquor was formed, and a black powder was left, 

 which was lixiviated upon a filtre by boiling water. The 

 liquid which had passed through the filtre was rendered 

 somewhat troubled by digestion with carbonate of ammonia, 

 and the precipitate thrown upon the same filtre. The li- 

 quor being now supersaturated by muriatic acid, and after ex- 

 pulsion of carbonic acid in a moderate heat, mixed with caustic 

 ammonia and muriate of lime in a well-closed bottle, no sensible 

 precipitate was formed ; a proof of the presence of fluoric acid. 

 6, The black powder was dissolved in muriatic acid. There 

 was evolved at first a sensible smell of sulphuretted hydrogen, 

 which was soon displaced by a strong smell of chlorine; a pel- 

 licle of sulphur appeared at the same time upon the liquor. 

 The muriatic solution was evaporated to dryness, and silica 

 separated, which after ignition weighed 0.5661 gr.=35.271 p.c. 

 c, The fluid was then boiled with an excess of a solution of 

 pure potash ; the alkaline liquor separated by the filtre from 

 the brown precipitate, supersaturated by muriatic acid, and 

 precipitated by caustic ammonia. The glycine weighed after 

 ignition 0.1482 gr. = 9.234 p. c. It was dissolved in muria- 

 tic acid, and the solution put in digestion with an excess of 

 carbonate of ammonia. A white earth was left undissolved, 

 which, even by a much larger quantity of carbonate of ammonia, 

 was not taken up, and which after ignition weighed 0.0232 

 gr. = 1.445 p. c. When dissolved in sulphuric acid, and 

 mixed with sulphate of potash, two small crystals of alum 

 were formed. Nevertheless this earth was not pure alumine, 

 for it produced, when treated with nitrate of cobalt before the 

 blow-pipe, not that fine blue colour, which characterises pure 

 alumine, but became, on the contrary, bluish-black, and this 

 colour was scarcely to be distinguished from that afforded by 

 pure glycine with this metallic salt. It seems, therefore, that 

 a certain quantity of glycine in chemical combination with 



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