4 S EXPERIMENTS on IVHINSTONE and LAVJ. 



of whinftone. The production of this intermediate fubftance, 

 which much refembled the liver of an animal, is accom- 

 panied with fome curious particulars, which I fhall enumerate 

 and explain in another part of this paper. On fome occafions, 

 too, I obtained a vitreous mafs in which were a multitude of 

 little fpheres, having a dull or earthy fracture. 



At laft, on the 27th of January, I fucceeded completely in 

 the object I had in view. A crucible, containing a quantity 

 of whinftone, melted in the manner above_defcribed, being re- 

 moved from the reverberatory, and conveyed rapidly to a large 

 open fire, -was immediately furrounded with burning coals, and 

 the fire, after 'being maintained feveral hours, was allowed to 

 go out. The crucible, when cold, was broken, and was found 

 to contain a fubftance, differing in all refpects from glafs, and 

 in texture completely refembling whinftone. Its fracture was 

 rough, ftony and cryftalline ; and a number of fhining fa- 

 cettes were interfperfed through the whole mafs. The cryftal- 

 lization was ftill more apparent in cavities produced by air 

 bubbles, the internal furface of which was lined with diftinct 

 cryftals*. 



Having fhewn this refult to feveral of my friends, Dr Hope 

 regretted that the fubftance, previoufly to its artificial cryftalli- 

 zation, had not been reduced to the ftate of folid glafs ; fince 

 the adverfaries of the fyftem might allege, that, during the ac- 

 tion of heat, the original cryftallized texture of the ftone had 

 never been completely deftroyed. Being convinced of the pro- 

 priety of this obfervation, I determined, in future, to reduce the 

 ftone firft to glafs, and to perform the cryftallization after a fe- 

 cond fufton. 



For this purpofe, with the amftance of Dr Kennedy, to whofe 

 co-operation I am greatly indebted for the fuccefs of all the fol- 

 lowing experiments, I reduced a quantity of the fame whinftone 



to 



* I showed this refult at a meeting of the Society on 5th of February. 



