446 PHILOSOPHICAL TRANSACTIONS. [aNNO 1794. 



XXI F. Of a Mineral Substance, called Strontionite *, in which are exhibited its 

 External, Physical, and Chemical Characters. By Mr. John Godfrey 

 Schmeisser, F.R.S. p. 418. 



This substance has obtained its name from the place Strontion, in Scotland, 

 where it is found in granite rocks, accompanied by galena and witherite, which 

 latter is described by Dr. Withering in the Phil. Trans. 1784. On all the spe- 

 cimens which I have seen of this substance, I could not discover any regular 

 crystallized shape, like the witherite. The specimen which I submitted to expe- 

 riments, was in solid masses of a fibrous texture, apparently composed of long 

 fibres, closely adhering to each other, and disposed in a radiated manner; its 

 colour was an asparagus green, which appeared deeper towards the centre of the 

 mass; when broken, the surface was a little shining in certain directions, the 

 fragments rather bar-like, and somewhat brittle. Some specimens exhibit only 

 light shades of this colour, and appear to be composed of long thin bars, which 

 are often separated from each other towards the extremity. The specimen which 

 I examined, and used for experiments was semi-transparent, but the most part of 

 it rather inclining to opaque. As to hardness, its surface could be scratched with 

 a hard knife, but not scraped. Its specific gravity I found as 3.586, compared 

 to distilled water of 6o° temperature. Properties of the substance. — The first 

 experiments, which pointed out a distinction between its basis and the ponderous 

 earth of Scheele, were made, at Dr. Crawford's desire, by his assistant Mr. 

 Cruikshank, and were afterwards repeated by himself; the account of which is 

 inserted in the 2d vol. of the Med. Communications. 



Exper. 1 . I reduced a certain quantity of the substance to a very fine powder, 

 and boiled it in water for some time, but no solution took place. 



Exper. 1. With acids. It was not afi^ected by sulphuric acid; but was entirely 

 soluble in nitric and muriatic acid, with a strong effervescence, during which a 

 great quantity of gaz was disengaged, which when tried, was entirely absorbed 

 by lime-water, extinguished flame, and had no smell. 



Exper. 3. Diluted sulphuric acid dropped into a diluted solution of this sub- 

 stance in nitric and marine acid, occasioned a white powdery precipitate, which 

 was insoluble in water. 



Exper. 4. A piece of the substance was exposed to the action of the blow-pipe, 

 did not crackle nor split asunder, nor did it melt when even exposed to white heat; 

 but it discovered a very bright phosphorescent light, became more brittle, and 

 had lost its greenish cast; it was then partly soluble in water. It only lost a 

 very little of its weight, when exposed for a long time to white heat, but it then 

 still effervesces with acids. 



* Since calltd strontitos, and its pure earth, strontia. See Dr. Hope's excellent analysis of this 

 mineral in the -Ith vol. of the Trans, of the u. s. of Edinb. 



