182 OX THE ORIGIN OF COAL. [X. 



I further said, " It will be seen from this comparison that in ulti- 

 mate composition cork and lycopodium are nearer to lignite than 

 to woody fibre (cellulose), and may be converted into coal with far 

 less loss of carbon and hydrogen than the latter. They, in fact, 

 approach closer in composition to resins and fats than to wood ; and, 

 moreover, like these substances, repel water, with which they are 

 not easily moistened, and are thus able to resist those atmospheric 

 influences which effect the decay of woody tissue." 



The nitrogen present in the lycopodium spores, as remarked by 

 Dawson, " no doubt belongs to the protoplasm in them, which would 

 soon perish by decay ; and, subtracting this, the cell-walls of the 

 spores and the walls of the spore-cases would be most suitable material 

 for the production of bituminous coal. But this suitableness they 

 share with the epidermal tissue of the scales of strobiles and of 

 the stems and leaves of ferns and lycopods, and above all with 

 the thick corky envelope of the stems of sigillarise and similar 

 trees .... which, from its condition in the prostrate and in the erect 

 trunks contained in the beds associated with coal, must have been 

 highly carbonaceous and extremely enduring, and impermeable to 

 water." The substance known as mineral charcoal is, according to 

 Dawson, derived from woody tissue and the fibres of bark. (See in 

 this connection his paper on the Conditions of the Accumulation of 

 Coal, Quarterly Geological Journal, XXII. 95.) 



[NOTE to page 180. The petroleum of Pennsylvania, according to Pelouze 

 and Cohours, yields by fractional distillation various liquids having the 

 common formula CH,n+, (C = 12), the value of n ranging from 4 to 15, 

 (corresponding to C 8 H, . . . C M E U in the notation adopted in the preceding 

 pages), and the boiling-point from to 160' C. Of this series, which also in- 

 cludes the paraffines, the first term is marsh-gas or formene, and the second and 

 third belong to the ethylic and propylic groups, being C,H 4 , C 4 H a and C 4 H 8 in 

 the above notation. The latter two, according to Ronalds, are found in solu- 



tlie crude petroleum. The researches of Foucou and Fouqud (Comptes 

 Rendus, November 23, 1868) show that while the inflammable gases from the 



<1 Burning Spring near Niagara Falls, and from an oil-well in Wirtz 



, West Virginia, are marsh -gas with small admixtures of carbonic acid, 

 the gases from an oil-well in Petrolia, Ontario, and from Fredonia, Chatauque 



, New York, are mixtures, in about equal parts, of the second and third 

 of the above series. The gas at the latter locality is from a 

 well sunk into the Genessee slates, at the summit of the Hamilton formation, 

 which gives no petroleum, but has for many years furnished the supply of 

 gas for lighting a small town. The gas from an oil-well in Venango County, 

 Pennsylvania, contained besides the first three bodies of the series a portion 

 of the fourth, C.H,,. Neither acetylene, free hydrogen, carbonic oxide, nor 

 olefiant gas or its homologues were detected.] 



