E^SUM^ AND GENERAL DISCUSSION. 



539 



Furtliermore, Bischof states as additional evidence of the truth of 

 bis assertion that carbon cannot have existed in the primeval earth, that 

 this clement is not found in the nnstratified crystallhic rocks which, 

 according to the views of the plutonists, were lifted up from beneath. 

 (** Da die gauze Gruppe von nicht geschichteten krystalliuischen Ge- 

 steineUj welche nach Ansicht der Plutonisten von unten heraufgehoben 

 werden, in ihrcr Masse keincn Kohlcnstoff enthalten," etc.) 



This, again, is an entire mistake on the pai't of Biscliof. The lar- 

 gest and most important deposit of graphite in the world — -that of the 

 Alibcrt mine — is described by various geologists who have seen it as 

 occurring in granite, or as lying between granite and syenite. In fact, 

 the normal occurrence of graphite may be said to be in the older gneis- 

 sic and schistose rocks, in which it either forms lenticular masses of 



greater or less size, or is disseminated through the rock in scales, or 

 tliin layers. 



One of the most celebrated known localities of graphite is in Bavaria, 

 in the so-called Passauer Wald, where it has been for a long series of 

 years extensively worked. Giimbel has made a thorough investigation 

 of this region. The rock in which the graphite is contained is gneiss, 

 called by this geologist " Graphitgneiss," because the mineral in epics- 

 tion is disseminated through the rock just as the mica is, forming 

 apparently an integral part of it ; not — as Giimbel thinks is evident — 

 replacing the mica, but being an original constituent of the gneiss. To 

 use his own words :'" We must therefore consider the graphite to be as 

 much a primary formation [primiire Bildung] as iiro the other minerals 

 of the gneiss, of which it makes a constituent part" 



Graphite occurs in the crystalline limestones associated with the 

 older crystalline or azoic rocks ; but not — so far as we know — aggre- 

 gated into masses of sufficient size to be anywhere an object of prof- 

 itable exploration. The normal mode of occurrence of graphite in 

 limestone seems to be in the form of thin scales disseminated through 

 the rock, and these scales are larger and more distinctly developed 

 where the limestone is most crystalline. 



Indeed, so far are the statements of Bischof from the truth, that it 

 may be stated, as the result of geological observation up to the present 

 time, that true graphite is '^almost exclusively confined to granite, 

 gneiss, quartz, mica-slate, crystallized limestone, and the older slates." * 



That graphite has been formed from vegetable matter, at least in a 

 manner similar to that in which coal has been, as is claimed by so 



* Jukes and Gdkie, " The SUulont's Manual of Guology," 3d edition, 1872, p. 56. 



