138 GEOLOGY OF THE LOTHIANS. 



to effect this object were only partially successful ; the pro- 

 duct of the slow refrigeration was not in a vitreous state, 

 but still it had not the crystalline appearance of the whin- 

 stone ; sometimes it had a liver-like appearance, and at 

 others was a dull vitreous mass, containing innumerable little 

 spheroids and having a dull earthy fracture ; at last, how- 

 ever, Sir James succeeded completely in the object which 

 he had in view. A crucible, containing melted greenstone, 

 was removed from the reverberatory, placed in a large open 

 fire, and surrounded with burning coals. The fire " after 

 being maintained for several hours was allowed to go out, 

 and the crucible when cold was broken, and was found to 

 contain a substance differing in all respects from glass, and 

 in texture completely resembling whinstone. Its fracture 

 was rough, stony, and crystalline ; and a number of shin- 

 ing facettes were interspersed through the whole mass. The 

 crystallization was still more apparent in cavities produced 

 by air bubbles, the internal surface of which was lined with 

 distinct crystals.'" — P. 48. The fragments of greenstone, 

 however, which had been thus artificially crystallized had 

 not been previously reduced to the state of glass, and 

 therefore the experiment might be liable to rejection as 

 inconclusive by those who advocated Neptunian principles. 

 To obviate this, however, Sir James Hall determined, on 

 the suggestion of Dr Hope, the Professor of Chemistry, to 

 " reduce the stone first to glass, and to perform the crystal- 

 lization after the second fusion. 1 ' 



We shall now notice the results which were obtained. 

 The greenstone of Bell's Mills was fused and quickly cooled 

 into a black glass, as in former experiments ; " a crucible, 

 filled with fragments of this glass, being then exposed to a 

 heat, which from previous trials was judged to be more 

 than sufficient to reduce its contents to fusion, the fire was 



