4^ EXPERIMENTS on TVHINSTONE and LAVJ. 



of whinflonc. The produdlion of this intermediate fubflance, 

 which much refembled the Uver 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 fphcres, having a dull or earthy fraAure. 



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

 the objedl I had in view. A crucible, conraining a quantity 

 of whinftone, melted in the manner abovedefcribed, 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 refpeds from glafs, and 

 in texture completely refembling whinftone. Its fradlure was 

 rough, ftony and cryftalllne ; 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 diftin<5l 

 crvftals*. 



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

 r-egi'etted that the fubftance, previoufly to its artificial cryftalli- 

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

 the adverfavies 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 obfcrvation, I determined, in future, to reduce the 

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

 cond fufion. 



For this purpofe,with the afliftance 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 jth of February. 



