116 Dr Turner on the Means of Detecting, $c. 



then the assay gives a strong brown stain to moistened tur- 

 meric paper. The property of strontianite in colouring flame 

 is lessened by mixing it with the flux. When celestine is ex- 

 posed in like manner, no redness appears at first ; but if a 

 strong heat be kept up for a minute or two, the salt is de- 

 composed, phosphorescence commences, followed by a red 

 hue, and the assay is found to be alkaline. This change is 

 facilitated by mixing the celestine with the flux of bisulphate 

 of potash and fluor-spar. Complete fusion then occurs, 

 though without the least trace of a red colour ; but, on con- 

 tinuing the blast, the assay gradually becomes solid, and then 

 the strontia is speedily reduced to the caustic state. I have 

 been thus particular in describing these appearances, because 

 they afford us a useful test to distinguish the native salts of 

 strontia from those of baryta; while they cannot be confound- 

 ed with the effects produced by lithia. 



The carbonate and sulphate of lime give rise to the same 

 phenomena, though their effect is less distinct ; and the colour, 

 as in the case of strontia, does not appear till the lime is re- 

 duced to its caustic condition. I have examined a consider- 

 able number of siliceous minerals containing lime, in some of 

 which, as datolite and apophyllite, that earth is present in a 

 large proportion ; but none of them, whether alone, or with 

 flux, give a red colour to the flame of the blowpipe. It is 

 probable, from this fact, that strontia, did it chance to occur 

 in a siliceous mineral, would likewise be inert ; or if it did 

 redden the flame, it would be under circumstances which 

 would distinguish it from the action of lithia. For the strontia 

 would be converted into a sulphate by the flux, and could 

 not produce its effect till that salt was decomposed. 



It is very desirable that the presence of potash and soda in 

 minerals could also be discovered by the blowpipe. The 

 pale lilac produced by potash, though it enables a salt of that 

 alkali to be readily distinguished from the salts of soda or 

 lithia, is too faint for affording a test of its presence in mine- 

 rals, unless it exists in considerable quantity. The property 

 soda possesses of communicating a yellowish colour, and of 

 making the flame larger at the same time, may be turned to 

 some advantage ; for several minerals that contain soda act 

 on the blowpipe flame in the same manner as soda itself, from 



