378 Eemarks on Keilhaii's Theory of Granite. 



shaping of the wreath escape us, but this is no reason why we 

 should doubt the existence of snowfalls and tempests ?* 



* In regard to the discussions connected with Professor Keilbau's geolo- 

 gical opinions, wc subjoin the following extract from a letter which we had 

 the pleasure of receiving from him. — Edit. " My fundamental idea is, that 

 there exist gcuhi/'ical nccessltks which must be respected, even though they 

 should be opposed to some theorem of chemistry, — a science which, like geo- 

 logy, is a progressive one, — and that at present it ought to be our especial 

 object to make ourselves fundamentally acquainted with those necegsities, 

 those clear facts which atlmit of only one interpretation, and which lead di-> 

 rectly to axioms, just as well as chemical experiments. In the report of 

 M. Berzelius to the Swedish Academy, wlicre he has discussed my memoir, 

 the conclusion he draws is simply this : By chemical analysis we do not find 

 the same component parts in granite as in argillaceous slate ; it is therefore hn- 

 po*s'Me that the first can be a metamorphosis of the otlicr. Tlierefore the geo- 

 logical facts are here of no consequence. In my opinion, on the contrary, the 

 geological facts are in some cases so positive as to the transformation of the 

 slate into granite, &c. that absolute confidence cannot be accorded to chemical 

 analyses, or rather to chemical ideas deduced from tliem, which do not agree 

 with the geological idea of transforuiations. In geology and in chemistry, 

 we endeavour to observe facts ; if this object were possible in the greatest 

 degree of perfection, the two sciences would always be in harmony ; but ob- 

 servations and researches being always more or less imperfect, there result 

 discrepancies ; and here I maintain, that it ought not to be considered that 

 it is the geologist in every case who has observed the most imperfectly ; I 

 believe that there are plicnomena, at the solution of wliich the geologist can 

 arrive before the clicmist, by following the path of pure experience. It is 

 nevertheless true that such cases have hitherto been rar-e, and that in geo- 

 logy, the practice has rather been to advance at full gallop on the path of 

 hypothesis, than to seai-ch carefully after conclusive facts. 



" In the report just mentioned, our distinguished chemist grants the ex- 

 istence of chemical actions in solid bodies, but he does not believe that the 

 force operating in them has performed so important a part as I must sup- 

 pose, in admitting the successive granitification of slates, &c. But of that 

 it is for geologists to judge, and they should not forget the views of modem 

 physics respecting a perpetual molecular movement of a mass apparently in 

 repose. Nevertheless, geologists themselves are perhaps at present but 

 little in a condition to discuss fairly this question ; for they seem to me too 

 much carried away by the ' doctrine ' of the internal heat of the globe. The 

 following is a striking circumstance of the present time. Geologists who 

 are Vulcanists, require the decision, that the earth is in a state of fusion at 

 a short distance from the surface ; and natural philosophers of distinction 

 have not hesitated to pronounce such a decision, merely to partake in the 

 honour of having constructed the definitive theory of unstratificd formations, 

 of chains of mountains, of volcanos, of earthquakes, &c. For myself, at least, 

 I see no other motive ; -for if it were not desired to secure pai-t of this glory. 



