446 SUPPLEMENTARY NOTES. 



finite distance before the first of the six days described in the 

 I Mosaic History of creation, I see no reason for extending the 

 length of any of these beyond a natural day; and I suppose that an 

 interval sufficient to afford all the time required by the Phenomena 

 of Geology, elapsed between the prior creation of the Universe 

 recorded in the first verse of Genesis, and that later creation, of 

 which an account is given in the third and following verses, and 

 which has especial relation to the preparation of the Earth for the 

 abode of man. At p. 29, it is shown in a Note by Prof. Pusey, 

 that the notion of such a prior act of creation was entertained by 

 many of the Fathers of the Church, and also by Luther. 



P. 42. Professor Kersten has found distinctly formed crystals 

 of prismatic Felspar on the walls of a furnace in which Copper 

 slate and Copper Ores had been melted. Among these pyro- 

 chemically formed crystals, some were simple, others twin. 

 They are composed of Silica, Alumina, and Potash. This dis- 

 covery is very important, in a geological point of view, from its 

 bearing on the theory of the igneous origin of crystalline rocks, 

 in which Felspar is usually so large an ingredient. Hitherto 

 every attempt to make felspar crystals by artificial means has 

 failed. See Poggendorfs Annalen, No. 22, 1834, and Jameson's 

 Edin. New Phil. Journal. 



Professor Mitscherlich has also succeeded in producing syn- 

 thetically, by the action of Heat, artificial crystals of Mica; these 

 are difficult to make, unless the ingredients pass very slowly from 

 a fluid to a solid state; as they are supposed to have done, in an 

 infinitely greater degree, in the formation of Granite, and other 

 Primary Hocks, of which Mica forms a large ingredient. In more 

 recent igneous rocks of the Trap formation, in which Mica is rare, 

 and crystals of Pyroxene abound, it is probable that the cooling 

 process was much more rapid, than in rocks of the Granitic series; 

 and crystals of Pyroxene have been formed synthetically by 

 Mitscherlich, from their melted elements, under much more rapid 

 cooling than is required to produce artificial Mica. 



The experiments of Sir James Hall, on whinstone and lava, 

 made in 1798, first showed the efiects of slow and gradual cool- 

 ing in reproducing bodies of tliis kind in a crystalline state. 



