176 BITUMENS AND PYROSCHISTS. [X. 



one from Bastennes gave C M H|,0 7 , while that from near Naples 

 may be represented by C^H^Oj, and an asphalt from Mexico gave 

 to Regnault C^H^Oj. The analyses of Johnston shows that guaya- 

 quillite and berengelite do not differ greatly from these in the pro- 

 portions of carbon and hydrogen. Passing from the asphalts to 

 idrialine, the results of whose analysis are represented by C^Hg, we 

 have a hydrocarbon with a minimum of hydrogen. It is well in 

 this place to compare the above results with the formula C^H^O^ , 

 which is deduced from Wetherell's analysis of the so-called albertite 

 or Albert coal. A "lignite passing into mineral resin" gave to 

 Regnault C 24 H 15 8 . 8 , and five analyses of bituminous coal by the 

 same chemist yield from C 24 H 8 . 9 to C 24 H 10 3 . 3 , while the mean 

 composition deduced by Johnston from several analyses of coal was 

 C 24 H 9 , with from O a to 4 . From these results it will be seen that 

 some asphalts approach bituminous coals in composition. That of 

 Naples, which is completely fusible at 140 C., contains less hydro- 

 gen and more oxygen than the albertite, while the idrialine is near 

 in composition to certain bituminous coals, which are thus almost 

 isomeric with some fusible bitumens ; so that it is easy to conceive 

 the same organic matters giving rise either to coal or to asphalt, 

 even without losing their structure. Such appears to be the case in 

 the tertiary strata of Trinidad and Venezuela, the bitumen of which, 

 from Mr. "Wall's researches, seems to have arisen from " a special 

 mineralization of vegetable remains in certain strata, which has 

 resulted in the production of bitumen, instead of coal or lignite." 

 This conversion, according to him, "is not attributable to heat, 

 nor of the nature of a distillation, but is due to chemical reactions 

 at the ordinary temperature, and under the normal conditions of 

 climate." Mr. Wall also describes portions of wood from these 

 deposits, which have been partially converted into bitumen, and 



simply the results of analysis, without attempting to fix the constitution of 

 tho matters in question. 



In the notation employed, H = 1, C = 6, and = 8. As it is not generally 

 used in the American Journal of Science, I have not thought necessary to 

 adopt, in this paper, the double equivalent of the latter elements, now em- 

 ployed by so many chemists. I may, however, call attention to the fact that 

 I was, I believe, the first to propose such a change, when, in 1853, I asserted 

 that the even coefficients of oxygen, sulphur, and carl ion in ordinary for- 

 mulas seem to furnish a conclusive reason for doubling thrir <-<|uivalents, or 

 for dividing those of hydrogen, chlorine, nitrogen, and the metals, according 

 as four volumes or two volumes are taken as the equivalent. (Theory of 

 Chemical Changes, Am. Jour, of Science (2), XV. p. 230. [Reprinted as 

 Essay XVI. of the present, volume.]) 



