Dr Turner on the Means of Detecting Lithia, $c. 113 



Art. XXI. — On the Means of Detecting Lithia in Minerals 

 by the Blowpipe* By Edward Turner, M. D. F. R. S. E. 

 &c. Lecturer on Chemistry, and Fellow of the Royal Col- 

 lege of Physicians, Edinburgh. Communicated by the 

 Author. 



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 cha- 

 racteristic colour to flame ; and this idea became more plau- 

 sible from the consideration, that the lithion-micas fuse 

 readily, and then tinge the flame red, while some other mine- 

 rals 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 following observation is in 

 support of this notion. A minute particle of spodumene, 

 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 mineral 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 communi- 

 cation of colour to flame, it is not always an essential condi - 

 tion. Thus, the carbonate of copper tinges the flame of a 

 candle green without fusing ; and if the carbonate of strontia 

 be strongly heated before the blowpipe, it phosphoresces re- 

 markably, and yields a red colour to the flame, though the 

 assay remains perfectly solid. Nor does a body cause its pe- 



" Head before the Royal Society of Edinburgh on the 5th December 1825. 

 VOL. IV. NO. I. JAN. 1826. H 



