Dr Reichcnbach on Petroleum or Mineral Oil. S79 



As it thus appears, that not a single distinct reaction, and 

 also not the slightest difference, is exhibited by these two oils, 

 I regard it as superfluous to pursue farther the comparison be- 

 tween two substances, against whose complete identity not a 

 proof presents itself. According to this investigation, I consi- 

 der myself entitled to draw the conclusion, that the newly dis^ 

 covered oil is not a iiew substance^ hut in fact nothing else than 

 a real and true petroleum. 



A confirmation of this might perhaps be brought from an 

 elementary analysis, and I shall not omit to effect this ; but, 

 since petroleun, taken as a species, is subdivided into a whole 

 series of kinds, from the naphtha through all the varieties of mi- 

 neral-oil to earthy pitch, and, since these are not simple, but 

 are mixtures of various substances, and in completely different 

 proportions ; it is evident that, until the component parts have 

 been obtained, an elementary analysis can afford no constant, 

 and indeed no diagnostic period. It can give nothing but an 

 approximation which will inform us in what part of the series 

 of petroleums the new oil ought to be placed. 



I endeavoured to extend similar observations to other descrip- 

 tions of coal. For this purpose I operated in the same man- 

 ner on several cwt. of brown coal from the quader-sandstone 

 formation of this neighbourhood. But I obtained no mineral 

 oil ; and the water of distillation did not even possess the smell 

 of petroleum. 



From this examination it appears, that the hitherto adopted 

 conjecture, that petroleum is the product of the action of a higher 

 temperature on combustible minerals, is not correct, and must 

 be abandoned. It is rather to be regarded as pre-existent in 

 coal, and as one of its component parts. The question as to 

 its existence in a state of chemical union cannot, it is true, be 

 decided ; but that such is the case is improbable, as the greater 

 part of the oil disappears when coal is exposed to the air. I am 

 rather inclined to believe, that it is merely mixed with the other 

 substances, and that, being very finely divided, it is retained 

 partly by adhesion. In order to expel it entirely, it is necessary 

 to heat the coal to the boiling point, that is to 167° C, which I 

 intentionally did not try, and which I advise those who wish to 

 repeat any experiments not to attempt, as, when the water has 

 entirely vanished, it is nearly impossible to heat the coal equally, 



