168 THE CANADIAN NATURALIST. [June 



liquid was yet so deep that the refrigeration from that time to 

 the present has not been suflBcient for its entire solidification, 

 is, however, not so probable. Such a crust on the cooling super- 

 ficial layer would, from the contraction consequent on the further 

 refrigeration of the liquid stratum beneath, become more or less 

 depressed and corrugated, so that there would probably result, as 

 I have elsewhere said, " an irregular diversified surface from the 

 contraction of the congealing mass, which at last formed a liquid 

 bath of no great depth, surrounding the solid nucleus." Geolo- 

 gical phenomena do not, however, in my opinion, afi'ord any 

 evidence of the existence of yet unsolidified portions of the 

 originally liquid material, but are more simply explained by the 

 third hypothesis. This, like the last, supposes the existence of a 

 solid nucleus, and of an outer crust, with an interposed layer of 

 partially fluid matter, which is not, however, a still unsolidified 

 portion of the once liquid globe, but consists of the outer part of 

 the congealed primitive mass, disintegrated and modified by 

 chemical and mechanical agencies, impregnated with water, and 

 in a state of igneo-aqueous fusion. 



The history of this view forms an interesting chapter in 

 geology. As remarked by Humboldt, a notion that volcanic 

 phenomena have their seat in the sedimentary formations, and 

 are dependent on the combustion of organic substances, belongs 

 to the infancy of geology. To this period belong the theories of 

 Lemery and Breislak (^Cosmos, v. 443 ; Otte's translation). 

 Keferstein in his Naturgeschichte des Erdkorpers, published in 

 1834, maintained that all crystalline non-stratified rocks, from 

 granite to lava, are products of the transformation of sedimentary 

 strata, in part very recent, and that there is no well-defined line 

 to be drawn between Neptunian and volcanic rocks, since they 

 pass into each other. Volcanic phenomena, according to him, 

 have their origin not in an igneous fluid centre, nor in an 

 oxydizing metallic nucleus (Davy, Daubeny), but in known 

 sedimentary formations, where they are the result of a peculiar 

 kind of fermentation, which crystallizes and arranges in new 

 forms the elements of the sedimentary strata, with an evolution 

 of heat as a result of the chemical process (^Naturgeschichte. vol. 

 i. p. 109; also Bid!. Soc, Geol. de France [1], vol. vii. p. 197). 

 In commenting upon these views (^Am. Jour. Science, July, 

 1860), I have remarked that, by ignoring the incandescent 

 nucleus as a source of heat, Keferstein has excluded the true 



