172 Professor Keilhau on Unstratified 



selves have also been very different.* It will be remem- 

 bered, that just a short time ago Fuchs, no mean chemical au- 

 thority, took up the doctrine of Neptunism. In short, it is a 

 pure fiction that chemistry is in possession of an immovable 

 foundation on which our knowledge respecting the origin of 

 the crystalline silicide rocks should rest. In the next place, 

 it may probably come to pass, that when it is decided before 

 a perfectly impartial tribunal^ whether, in the case before us, 

 Epigenism may not have as good claims to the approbation of 

 chemistry as Volcanism, the answer may be in the affirmative. 

 If the discussions regarding the processes which have been de- 

 signated by the name of cementation, regarding what are 

 termed *' actions lentes^^ regarding molecular movements in 

 solid bodies, &c., have not materially assisted us in under- 

 standing the phenomena on which such discussions turn ; still 

 these phenomena, which chiefly lie in the more limited sphere 

 of investigation of chemistry, are sufficient of themselves to 

 shew, that that description of nature''s actions which is to be 

 discerned by means of the study of the epigenetic rocks, can 

 also be satisfactorily recognised elsewhere, and is certainly 

 quite normal, t 



It must undoubtedly be chiefly owing to want of knowledge 

 of the subject, that the question as to the formation of gran- 

 ite and the other rocks more or less similar to it, has been 

 treated in the manner mentioned above. An intimate ac- 

 quaintance with more than one part of the subject is requisite ; 

 but this is, above all, necessary with regard to the mode of oc- 

 currence of these rocks, their relations to other rocks, and, in 

 short, all the phenomena and circumstances which can interest 

 geologists. A proper knowledge of this kind, however, is 

 partly rvanting even in those who are considered as the greatest 



• Upon this subject I have fully expressed my opinion in my little publica- 

 tion, entitled, Einiges gegen den Vulkanismus, p. 65-68. 



t One of the most interesting of the newer facts connected with this subject 

 is the transmutation of old glass, regarding which Brewster made a communica- 

 tion to the British Association at Glasgow in 1840. The homogeneous mass pro- 

 duced by fusion and subsequent cooling, had, according to him, acquired a hete- 

 rogeneous and crystalline structure ; the metallic particles had separated them- 

 selves, and the siliceous particles " had resumed their position as regular crystals, 

 and arranged themselves circularly round the centre of decomposition." The glass 



