XL] GRANITES .AND GRANITIC VEIN-STONES. 189 



mode of formation, endogenous granites. They are to the 

 gneisses and mica-schists, in which they are generally enclosed, 

 what calcite veins are to stratified limestones, and although 

 long known, and objects of interest from their mineral con- 

 tents, have generally been confounded with intrusive granites. 



8. Scheerer, in his . famous essay on granitic rocks, which 

 appeared in the Bulletin of the Geological Society of France in 

 1847 (Vol. IV. p. 468), conceives the congealing granitic rocks 

 to have been impregnated with " a juice," which was nothing 

 else than a highly heated aqueous solution of certain mineral 

 matters. This, under great pressure, oozed out, penetrating 

 even the stratified rocks in contact with the granite, filling 

 cavities and fissures in the latter, and depositing therein crys- 

 tals of quartz and of hornblende, the arrangement of which 

 shows them to have been of successive growth. Neither 

 Scheerer nor Virlet d'Aout, who supported his views, however 

 (Ibid., IV. p. 493), extended them to feldspathic veins, though 

 Daubree, at an earlier date, had described certain granitic veins 

 in Scandinavia as having been formed by secretion, rather than 

 by igneous injection, as maintained by Durocher. 



9. Elie de Beaumont, starting from the hypothesis of a 

 cooling liquid globe, imagined " a bath of molten matter on the 

 surface of which the first granites crystallized." From the ruins 

 of these were formed the first sedimentary deposits, but directly 

 beneath were other granitic masses, which became fixed imme- 

 diately afterward. "Some parts of these masses, coagulated 

 from the commencement of the cooling process, but not com- 

 pletely solidified, were then erupted through the sedimentary 

 deposits " just mentioned. " In these jets of pasty matter " 

 were contained many of the rarer elements of the granitic mag- 

 ma, which were thus concentrated in the outermost portions of 

 the granitic crust, and in the ramifications formed by these 

 portions in the masses through which they were forced by 

 the eruptive agents. Those portions of the granitic masses, 

 and their ramifications, in which these rarer elements are con- 

 centrated, are distinguished from the rest of the masses alike 

 by their exterior position and their peculiar structure. They 



