﻿ANNIVERSARY ADDRESS OF THE PRESIDENT. xlv 



perseverance in laborious research so peculiarly characteristic of his 

 countrymen. His recorded experiments extend over a period of 

 more than thirty years. His ' Lehrbuch,' even in the English trans- 

 lation in a condensed form (executed with the cooperation of the 

 author, under the auspices of the Cavendish Society), does not appear 

 to have received from the geologists of this country a due attention, 

 while he is constantly referred to as a high authority by the most 

 eminent geologists of France and GeiTnany. 



The agency of water in the formation of minerals was shown nearly 

 forty years ago by Becquerel, who succeeded in obtaining by a humid 

 process galena, sulphuret of antimony, and other minerals occurring 

 in veins. M. Scheerer*, in an elaborate memoir on the plutonic 

 nature of granite, in 1846, on a review of the chemical and mechanical 

 constitution of that rock, and of the many accessory minerals it often 

 contains, and especially their different degrees of fusibility and the 

 different temperatures at which they crystallize, arrived at the con- 

 clusion that the various phenomena tbey exhibit, as simple minerals 

 and in combination as a rock, can only be explained by the com- 

 bined action of heat and water. He tells us that he began to study 

 the granitic rocks of Norway in 1833, fully impressed with a belief 

 in the plutonic (that is, the solely igneous) origin of granite, but 

 that the result of a most careful research was an entire overthrow 

 of his early creed, and that "l'idee la plus juste que Ton peut se 

 former sur l'origine de ces roches est celle qivi attribuerait aux deux 

 elements, a l'eau et au feu, une egale puissance creatrice." M. Elie 

 de Beaumont, in 1847, in his very instructive essay " Sur les ema- 

 nations volcaniques et metalliferes," brings forward numerous in- 

 stances which appear to him to prove the existence of water in the 

 constitution of eruptive rocks and mineral veins. Thus, while the 

 igneous fusion of granite is, in his opinion, proved beyond all doubt 

 by many phenomena that accompany it, he considers it to be no 

 less capable of proof that water must have entered into its compo- 

 sition while in that state. He observes that M. Scheerer of Chris- 

 tiania has given many reasons why granite in fusion must have 

 contained water, that it was in combination with it at the time of 

 its eruption, and that it was retained until after the final cooling of 

 the granite ; for many simple minerals containing water as a con- 

 stituent are found in that rock. M. de Beaumont conceives that 

 there is, in truth, no reason against believing that granite contained 

 water at the time of its eruption ; for the lavas of existing volcanos, 

 at the time of their ejection, contain a large amount of water, 

 which in part separates in the form of vapour, but is not entirely 

 dissipated for many years f. In treating of different kinds of 



* Bulletin de la Soc. Geol. de France, 2de serie, vol. iv. p. 468. 



t " Dans les exhalaisons volcaniques, il est un corps qui n'a pas tout d'abord 

 fixe 1' attention, parce que, sous 1' empire des idees anciennes, il semblait tout a, 

 fait inerte, sur tout en presence des mineraux dont il s'agit d'expliquer la forma- 

 tion, mais auquel pourtant le premier role parait devoir etre devolu, dans les 

 phenomenes metamorphiques aussi bien que dans les eruptions des volcans: ce 

 corps c'est l'eau, qui se trouve dans ces exhalaisons, non en quantite minime, 

 comme les vapeurs, mais, au contraire, comme le produit a la fois le plus abondant 



