142 GEOLOGY OF THE LOTHIANS. 



racterized crystallites, that last mentioned having its felspars 

 entire, produced a substance like porphyry, in which the 

 white felspars were imbedded in a black crystalline basis. 

 The crystals formed in this basis are so complete in one 

 example, that they are seen projecting into the cavities and 

 standing erect on the external surface so as to make it 

 sparkle all over. These black crystals seem to be horn- 

 blende of new formation. We have found by some late 

 experiments that they are considerably more refractory than 

 the crystallite in which they lie, and are equally infusible 

 with some species of natural hornblende. 1 '' — P. 53. 



Whin (Basalt) from the neighbourhood af Duddingston Loch. 

 " Its glass yields a fine grained crystallite, like to that 

 of the greenstone of Bell's Mills. 1 ' 1 — P. 54. 



Whin (Greenstone) of Salisbury Crags. 

 fc ' Its glass yielded a highly facetted crystallite, approach- 

 ing to the structure of the unfused basalt of Duddingston 

 Loch. ,, — P. 54. 



Whin (Syenitic Greenstone) from the rolled masses in the bed of 

 the Water of Leith. 



" In fusion and crystallization it resembled the other 

 whins. ,, — P. 55. 



Whin (Basalt) of the basaltic columns of Staffa. 



" It yielded a perfect and very hard glass, which, in a 

 regulated heat, produced a uniform stony crystallite, greatly 

 resembling the original. 11 — P. 55. 



Having performed the experiments on whinstone, the 

 unerupted lava of the philosopher whose opinions he had 

 adopted, Sir James Hall engaged in a series of experiments 



