326 F0COIDES IN THE COAL FORMATIONS. 



are heaped in great masses on sandy shores, they promptly decompose, passing first to a 

 black, soft paste, and then to a glutinous fluid of the same color, which exhales a strong 

 disagreeable odor, and penetrates the sand. Chemistry has not analyzed these matters 

 resulting from the decomposition of Hydrophytes, nor even species of marine Algae ;* and 

 therefore it is not proved that there exists a direct relation between them and petroleum. 

 Chemistry demonstrates, however, that petroleum and coal are both compounds of the same 

 elements ; and the former matter being proved of vegetable origin, the second is neces- 

 sarily, by induction, referred to the same.f And as some substances, like iodine, which 

 was formerly procured from marine plants only, are now more abundantly obtained from 

 petroleum, chemical analyses, I think, confirm in that way the relation between petroleum 

 and Hydrophytes. 



Though chemistry is not directly interested in it, it is but right to refer here to a pecu- 

 liar fact which bears upon the subject. The Alga?, especially the group of the Caulerpce, 

 feed some of the animals of the seas, remarkable for the size and the prodigious fatness of 

 their bodies. The green fat of the turtles, says Harvey,| so much prized by aldermanic 

 palates, may possibly be colored by the unctuous green juice of the Caulerpa;, on which 

 they browse. The same could be said of the color of the Devonian petroleum, which is 

 exactly that of the Chlorosperm Hydrophytes. It is not positively ascertained, I believe, 

 if whales and other marine mammifers of this kind, whose bodies are large reservoirs of 

 oily matter, are true Algas-feeders ; but when killed, the stomachs of these animals are 

 always found mostly filled with marine weeds. 



4 12. GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION OF PETROLEUM DEPOSITS AND 



FUCOIDAL REMAINS. 



A last argument, no less conclusive on the subject, is taken from the geological and also 

 from the geographical relation between deposits of petroleum and Fucoidal remains. 



Oil-bearing strata are seen in the Coal Measures mostly inferior to the big bed of coal 

 No. 1, which is often a cannel coal ; and sometimes also, but rarely, at a higher horizon, as, 

 for example, below coal No. 3, and also coal No. 12, generally in more or less evident con- 

 nection with cannel coal. This has probably led to the opinion, still admitted by some 

 geologists, that all the deposits of petroleum owe their origin to a slow decomposition of 

 coal, under some peculiar influences. As there has not heretofore been observed any indi- 



* Prof. Liebig, to whom I wrote a rteumi of my opinion on the subject, with the request that he would point 

 out to me the result of chemical analysis of marine plants, if there were any, either in support or discredit of my 

 ideas, kindly answered : " That there were unhappily no analyses of species of Fucus, or of other Hydrophytes, 

 which could be used as affording support to my views. But that my arguments, based on exact researches, were 

 so conclusive, that for himself, at least, they had removed any doubt of the truth of the theory." 



f See, on this subject, a very remarkable and most instructive paper, by Sterry Hunt, in the American Journal 

 of Science and Arts (2), pp. 156 to 171. 



J Loc. cit., vol. i, p. 31. 



