58 Dr. T, Sterry Emit — On Chemical Geology, 



originated in the brains of their antagonists. " Farther, in a note to a paper on the 

 Microscope in Geology, in the Popular Science Review for October, he says, with 

 equal good taste and truth, *' the idea of a true dry fusion in nature exists only in 

 the brains of the ultra-neptunists or the luke-warm hydrothermalist," and asserts 

 that in igneous action the agency of water was always recognized. He alludes to 

 Poulett Scrope, who in 1824 put forth his views on the intervention of water in 

 giving liquidity to lavas ; but as Mr. Scrope himself tells us in his late paper 

 {Quart. Journ. Geol. Soc. xii. 343), his views were declared to be unchemical, 

 discredited, and ridiculed ; nor was it till in 1847, when Scheerer published his 

 remarkable essay on the origin of granites, {BuL Geol. Soc. Fr. [2] iv. 468, ) that 

 lithologists began to admit that water had intervened in the generation of granite 

 and other eruptive rocks. But our readers shall judge what value is to be attached 

 to Mr. Forbes's assertions in this matter. After Scheerer's view of aqueo-igneous 

 liquidity had been made known to the Geological Society of France, Durocher, as 

 the champion of the plutonists, maintained in opposition to it, the hypothesis 

 already referred to of a separation of the liquid globe into two layers, the lower 

 one heavier and basic, the upper lighter and acid, which by its solidification 

 gave rise to granite. While he declared that ^^ Scheerer's new theory has for its 

 principle the introduction of water in the solidification of granite rocks," Durocher 

 conceived all the water found in eruptive rocks to have been subsequently 

 absorbed by them {Bui. Soc. Geol. [2] iv, 1029, 1032). Riviere, following a second 

 communication by Durocher on the same subject, declares, "I think with 

 Durocher, that water has played no part (ji'a joue aucmi rSle) in the fo7mation of 

 granite,'''' and as to the rocks considered by Scheerer (granites, etc.), he asserts " the 

 geological position of these absolutely excludes the intervention^'' of water (Ibid. [2] 

 vii. 287). I might further quote Fournet, who in his Geologic Lyonnaise, strongly 

 maintains similar views to the above, and invokes in favour of his purely igneous 

 theory the results and the statements of Hutton and Hall, Lest, however, there 

 should be any mistake, and that the advocates of dry fusion, Durocher, Eiviere, 

 and Fournet, be, after all, ultra-neptunists, I shall cite Elie de Beaumont, who in 

 his classic essay on Volcanic Emanations, etc., (published in 1847,) Bid. Geol. 

 Soc. Fr. [2] iv. 1249, has admirably discussed the question before us, giving the 

 views of Fournet and Durocher, the former of whom explains the liquidity of granite 

 by a surfusion of the quartz, which melts at 2800° centigrade, but remains viscid at 

 much lower temperatures on cooling ; while Durocher, on the contrary, imagines 

 "a sort of fusible alloy" of the various elements, from which the feldspar and mica 

 crystallized. Eejecting these, which he designates 7i& '"'' purely igneous surfusion,'''' 

 he declares in favour of Scheerer's '■''altogether novel idea" of a condition of quasi- 

 fluidity at a low red heat, due to the intervention of water, and asserts that *' the 

 hypothesis of a primitive state of simple igneous fusion of granite, notwithstanding 

 the evidences brought forward in its favour, is no longer justified" {loc. cit. pp, 

 1305, 1311)- It is in the face of records like these, and despite the energetic pro- 

 test of plutonists against the possibility of the intervention of water, and in favour 

 of a dry fusion or a simply igneous fusion of the elements of granite, that Mr. 

 Forbes has the hardihood to assert that the intervention of water in igneous agency 

 "was always recognized by the plutonist." 



But I have not done with Mr. Forbes until he shall have shown how, with his 

 own theory of the earth, he explains the intervention of water in all igneous 

 rocks, which, as he declares, are outbursts from the still fluid interior of our globe. 

 How did the water find its way there, since, according to him, far above the 

 already solidified crust, this element at first formed a vaporous layer, separated 

 from the earth by a stratum of volatile chlorids and another of carbonic acid gas ? 

 In virtue of what law did this water, after its precipitation, diffuse itself through- 

 out the various layers of the liquid mass which still fills the centre of the earth, so 

 as to be present in every eruptive rock coming up from that great reservoir ? For 

 my part, I am inclined to say with Riviere, that the geological position of such 

 matters must "absolutely exclude the intervention of water;" and until Mr, 

 Forbes, or some other plutonist, shall have given a plausible hypothesis to explain 

 the fact, which he admits, of the universal diffusion of water in igneous rocks, I 

 prefer my own theory of their origin, namely, that the anhydrous and incandes- 

 cent nucleus of the globe is solid, and, except in its outer portions, takes no part 

 in volcanic or plutonic phenomena, which have their origin entirely in the stratified 



