Crystalline Silicide Slates. 163 



designation it was brought before the judgment-seat of che- 

 mistry. As those who adopted the doctrine of transmutation 

 had committed the fault of not distinctly separating what was 

 the incontrovertible result of geognostical observations from 

 those immature explanations with which they deemed it ne- 

 cessary to accompany this result, it thus undeniably acquired 

 an aspect of uncertainty. Thus proclaimed by its adversaries 

 to be a mere idea, and obscured in this manner by its champions, 

 it was rejected by the chemists, who estimated the whole ac- 

 cording to the subjoined chemical suppositions. " The most 

 distinguished chemists of our time," says Leonhard, " have, 

 as was to be expected, expressed themselves strongly against 

 the transmutation theory ; they characterized it as founded 

 on an insecure basis. Although there are many of the higher 

 problems of geology which chemistry may not be in a position 

 to solve, yet it certainly does not become the former science to 

 hasten beyond the latter ; and especially in such bold hypo- 

 theses as those in this theory, geologists require recognition 

 on the part of chemistry as a guarantee. Can we blame chemists 

 for keenly finding fault with the adoption of obscure processes 

 without taking into consideration the how and wherefore, 

 without naming the agent which produced these very strange 

 phenomena, without pointing out whence this or that ele- 

 ment in the newly produced formations was derived, and 

 without indicating the manner in which the others disap- 

 peared ? " Now, it is well to notice that, in this reasoning 

 of the influential author, those chemical speculations brought 

 forward by certain geologists, and which have produced mis- 

 belief regarding the result as to transmutations, are alone to 

 be understood as included in the expression insecure basis of 

 the " conversion theory ;'* for the true basis of our knowledge 

 of the conversions in question lies beyond the proper limits of 

 chemistry. When two equally good geological hypotheses, 

 which regard a subject of a chemical nature, stand side by 

 side, it is then quite proper that the decision should be referred 

 to chemistry. But we repeat it again and again, that this is 

 by no means the case here ; for, whoever wishes, can see, that 

 transmutations of uncrystalline strata into crystalline silicide 

 rocks have taken place. The question no longer turns by any 



