106 ■ Sir A. Crichton on the [Feb. 



cime, and various other bodies, when fused by the heat of a 

 volcano, unite to form these compounds, most of which appear 

 as perfect and beautiful crystals in the very substance and cavi- 

 ties of the fused mass. Lavas, basalts, volcanic pitchstone, 

 porphyries, &c. are full of such crystallized bodies, and throw a 

 light by analooy on the formation of granite, inasmuch as they 

 demonstrate the positive fact, that these crystalline substances, 

 bearing a close resemblance to the ingredients of this rock, may 

 be formed by igneous fusion ; and when to this is added the 

 results of Mi-. Micherlich's most ingenious experiments on the 

 artificial production of pyroxene and mica by fusion, the evidence 

 becomes almost complete. 



In the very substance and cavities of lavas, we meet with 

 amphigene, harmatome, feldspar, icespar, Thomsonite, arago- 

 nite, mica, amphibole, and augite, all in a crystallized state. It, 

 therefore, appears probable, that these crystalline bodies were 

 formed when the liquid lava allowed their elements to arrange 

 themselves according to their affinities. To suppose the cenfral 

 part of the earth a mass of higiily ignited liquid matter still 

 existing in a state of fusion is not consistent with any thing that 

 we know ; but as the brilliant discoveries of Sir Humphry Davy 

 in chemistry have demonstrated beyond the possibility of doubt 

 that all the earths are metallic oxides, it is not incongruous to 

 suppose that the nucleus of the earth was in toto, and still is in 

 part, in a completely metallic state, and that the granite crust of 

 the earth was formed by a general and contemporaneous oxida- 

 tion and consequent ignition of the whole of its surface. This 

 doctrine would account in a natural manner for the earthy and 

 alkaline oxides which are found in all the rocks and minerals 

 which we suppose to be of igneous origin, or, in other words, 

 for all those substances which have till of late been considered 

 as distinct earths and alkalies. It accounts not only for the 

 universality of the granite involucrum, but also for the similarity 

 of its composition ; for in fact, the granite is to be considered as 

 a mass of earthy oxides which were produced by the action oi 

 air and water, or watery vapours, on the metallic mass. When 

 we reflect for a moment on the intense heat produced by the 

 rapid oxidation of a very few grains of potassium or sodium, we 

 may conceive, if imagination can go so far, the more intense 

 heat of this globe during the simultaneous conflagration of the 

 whole of its surface. What a state of chaos and disorder, from 

 which was to spring a series of secondary causes, the agency of 

 which gave birth to a succession of others, each operating for a 

 time, and thus accounting for the whole order of the super- 



s' 

 structure. 



We must suppose the presence of water and atmosphere to 

 explain the oxygenation of the metallic mass, and it is conform- 



