1826.] ' On the Means of detecting Lithia in Minerals. 131 



Article X. 



On the Means of detecting Lithia in Minerals bi/ the Blowpipe.* 

 By Edward Turuer, MD. FRSE. &c. Lecturer on Chemistry, 

 and Feliow of the Royal College of Physicians, Edinbursjh. 

 (Read before the Royal Society of Edinburgh, Dec. 5, 1825.) 



At the conclusion of a paper on mica, published in the last 

 number of the "Edinburgh Journal of Science," I have made 

 some observations on the colour communicated to the flame of 

 a candle by the three alkalies, potash, soda, and lithia, by means 

 of which they might be readily distinguished from each other. 

 It seemed probable, from some facts there stated, that a body 

 must be fluid, in order to communicate its characteristic colour 

 to flame ; and this idea became more plausible from the consi- 

 deration, that the lithion-micas fuse readily, and then tinge the 

 flame red, while some other minerals which do not produce that 

 effect, though they contain lithia in considerable quantity, are 

 very difficult of fusion. Hence it occurred to me, that the last 

 description of minerals might also be made to redden flame, 

 could we by any means increase their fusibility ; and the follow- 

 ing observation is in support of this notion. 



A minute particle of spoduniene, previously reduced to fine 

 powder, and made into a paste with water, was exposed to the 

 flame of the blowpipe. For a time the mineral did not fuse, nor 

 was a trace of redness visible ; but by urging the heat, fusion did 

 at length occur, and at that instant the flame was tinged of a 

 red colour, though in a slight degree. On mixing the same mi- 

 neral with fluor spar, its fusibility was considerably increased, 

 and it gave a more distinct red hue to the flame. 



But though the liquid form is favourable to the communica- 

 tion of colour to flame, it is not always an essential condition. 

 Thus the carbonate of copper tinges the flame of a candle greea 

 without fusing ; and if the carbonate of strontia be strongly 

 heated before the blowpipe, it phosphoresces remarkably, aiid 

 yields a red colour to the flame, though the assay remains 

 perfectly solid. Nor does a body cause its peculiar colour to 

 appear tfom the mere circumstance of becoming fluid. Spodu- 

 mene, for example, can be made to fuse by the addition of the 

 carbonate of soda or potash, but no redness occurs. Fusion is 

 rendered still more perfect by the action of boracic acid, or the 



Ehosphate of soda and ammonia, but without a trace of redness 

 eing visible. 



These facts prove that a certain chemical condition of a body 

 is necessary, in order that it should produce its eftect on flame, 

 aud that this circumstance has a greater influence than form. 



• Edinburgh .lournal of Science. 



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