R^SUM]^, AND GENERAL DISCUSSION. 539 



Furthermore, Bischof states as additional evidence of the truth of 

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

 this element is not foiuid in the unstratiiied crystalline rocks which, 

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

 (" Da die ganze Gruppe von nicht geschichteten krj-stallinischen Ge- 

 steinen, welche nach Ansicht der Plutonisten von unten heraufgehoben 

 werden, in ihrer Masse keinen Kohlenstoff enthalten," etc.) 



This, again, is an entire mistake on the part of Bischof. The lar- 

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

 Alibert 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 

 thin layers. 



One of the most celebrated known localities of gi*aphite 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 ques- 

 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 [primare Bildung] as are the other minerals 

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



Graphite occurs in the crystalline limestones associated with the 

 older crj-stalline 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 Geikie, "The Stu-dent's Manual of Geology," 3d edition, 1S7'2, p. 56. 



