Peckham.] 45'^ [September 18. 



above 200° C, amounting to about thirty per cent, by measure. 

 When this dense portion amounts in other petroleums to about 

 seventy per cent., even should the lighter portions contain the 

 same principles, the question of similarity between the two oils 

 requires a comparison of the heavier quite as much as the lighter 

 portions. 



The small proportion of nitrogen foiiud in the petroleums of 

 the palaeozoic rocks of Penns3'lvania and Canada, might be derived 

 from any source to which the origin of petroleum has yet been 

 ascribed ; but when we pass up from those earlj^ formations 

 through the secondary rocks to the middle tertiary, to a deposit 

 rich in remains of the higher marine animals, in which cetacean 

 bones are as frequently met as any other fossil, and find an oil 

 comparatively rich in nitrogen, we are forced to admit that the 

 conditions of such theories are less in accordance with" facts. 

 The decomposition of carbonic acid and water by alkali metals 

 would scarcely be expected to produce an hydrocarbon of A^ery 

 unstable character, containing so large a proportion of nitrogen 

 as to render its decomposition analogous to putrefaction. Nor 

 should we expect such results from the partial decomposition of 

 vegetable matter, either of terrestrial or marine origin. The 

 small proportion of nitrogenous matter in the woody structure 

 of forest trees, and the still smaller propoilion in marine vege- 

 tation would fail to furnish the requisite amount, but in the 

 partial decomposition of the remains of highly organized ani- 

 mal tissue, we have an abundant source of nitrogen. 



Dr. Hunt has shown the possible derivation of compounds 

 having an equal number of equivalents of carbon and hydrogen, 

 similar to or identical with petroleum, from the decomposition 

 of animal tissue. He discusses this possibility however, onl}^ 

 with reference to the bitumens "met with in the lower Silurian 

 and Devonian limestones of marine origin."* 



It is not difficult to propose a theoretical decomposition of 

 many of the proximate principles of animal origin, which would 

 yield a substance having an equal number of equivalents of car- 

 bon and hydrogen. Thus, if six equivalents of carbonic acid 

 be removed from one equivalent of stearic acid, an equal number 

 of equivalents of carbon and hydrogen remain. One equivalent 

 each of stearate and oleate of glycerine, when deprived of six- 

 teen equivalents of carbonic acid and four of Mater, yield two 



* Am Jour. Sci. and Arts, (2) XXX. 162. 



