44 APPENDIX. 



chemical forces now in operation, and therefore it is a strictly 

 local and limited product, not necessarily connected with any 

 Carboniferous beds of comparatively high antiquity. As magnesite 

 exists in the vicinity, and that is certainly a I'ecent product, 

 arising from the decomposition of the exposed igneous rocks, so 

 infiltration, decomposition, and reconstruction of carbonaceous 

 materials, of whatever age, under the influence of chemical trans- 

 formation, may be producing diamonds at this moment, wherever 

 the needful conditions exist. 



An author of some distinction, M. Favre, Professor of Greology 

 at Geneva, has turned his attention to this very subject, and as 

 his paper on " Artificial Minerals" may not be generally known, I 

 will refer to it. [It is to be found in the JBidletin of the " Societe 

 Geoloffique de ITrance,''' vol. xiii., 2nd series.] He therein 

 reviews the experiments which, up to 18557 had been made in the 

 production of artificial diamonds, and refers to the experiments 

 of M. Jaquelain, who had procured from the diamond a carbon- 

 aceous matter having the aspect of coke, and those of M. Despretz, 

 who had proved that melted carbon and melted diamond are 

 nothing but graphite. This is akin to the idea of Glocker, of 

 Breslau, and of others before him, that diamond is an altered 

 coal. Petzholdt also found in difterent diamonds — especially the 

 brown — traces of similar organization to that of silicified vegetable 

 matter ; but Dufrenoy rejects the opinion of Liebeg, that they 

 can have a vegetable origin. 



M. Favre shows that, of thirty-four minerals found with diamond 

 (according to the catalogue of M. Denis), consisting of sulphurets, 

 carbonates, oxides, silicates, and native metals, thirty have been 

 artificially produced; and of the thirty, twenty-nine were produced 

 by the aid of volatile clilorides. 



If this be the case, though one of the conditions is heat, the 

 argument as to an igneous origin for diamond, because it is found 

 in association with minerals of igneous origin, must be abandoned 

 or modified. 



Ten years later. Professor Goppert, in his work " On the 

 Organic Nature of the Diamond," pointed out, as Jacquelain had 

 done, that it may be turned into coke. He says, that some must 

 have been soft, as they are superficially impressed by sand and 

 crystals ; that others contain crystals of other minerals, germs 

 of plants, and fragments of vegetation. Hence, it would certainly 

 appear that the origin of such diamonds cannot have been 

 igneous, and, I may add, assuredly not more so than those granitic 

 rocks I have already mentioned, that contain coal-measure plants. 

 He states further, in 1868, that he had a diamond which contained 

 dendrites, such as occurs on minerals of various origin ; that there 

 are at Berlin one which contains bodies resembling Protococeus 

 pluvialis, and another green corpuscles linked together, closely 



