180 ON THE ORIGIN OF COAL. [X. 



suggest analogies to the different transformations of organic tissues 

 which have resulted in the formation of anthracite, coal, lignite, 

 asphall, and petroleum, together with carbonic acid and gaseous 

 hydrocarbons as accessory products. (See note on page 182.) 



[The conclusions of the remaining nine pages of the above paper are 

 briefly summed up in the preceding one on The Oil-bearing Lime- 

 stones of Chicago. As a supplement to the remarks on the origin 

 of coal I may here make some extracts from a paper on Spore- 

 Cases in Coal, by Dr. J. W. Dawson, in the American Journal of 

 Science for April, 1871, including also a note by myself. Dawson 

 has there shown that while some exceptional beds of coal are to a 

 large extent made up of spores and spore-cases, probably of lepido- 

 dendron, it is by no means true that these are, as some have con- 

 jectured, the principal source of coal. On the other hand, it is clear 



posed to regard bone-gelatine as an analogous nitryl, C M HjoN 4 8 ; which 

 corresponds to one equivalent of glucose and four of ammonia, less 8 HO. 

 These uitryls, it was conceived, might, under certain conditions, regenerate 

 ammonia and a hydrate of carbon. I also adduced evidence that in a case of 

 diabetes, sugar was generated at the expense of ingested gelatine. (American 

 Journal of Science (2), V. p. 75; VI. p. 259; and Silliman's Elements of 

 Chemistry, p. 517.) The analyses of cartilage-gelatine, or chondrine, in like 

 manner correspond very nearly to a nitryl formed from C^H^O^. (cane-sugar) 

 and three equivalents of ammonia. The formula thus deduced, C^HiaNsOio, 

 requires 14.7 of nitrogen. 



In 1856, Dusart, starting, as he tells us, from my theoretical views, en- 

 deavored to produce the albuminoid bodies by the action of a solution of 

 ammonia on starch, lactose, or glucose at temperatures of 150 and 200 C. In 

 this way he obtained, after several days, an azotized body, which resembled 

 gelatine. It was precipitated by alcohol in elastic filaments, formed an 

 imputrescible compound with tannin, and, when heated, gave off the odor of 

 burning horn. Its proportion of nitrogen was 14.0 per cent, which is near 

 that of chondrine. (Comptes Rendus de 1'Academie, May, 1861, p. 974.) 

 Schoonbroodt has since asserted the possibility of converting sugar into an 

 albuminoid substance, and reiterated my suggestion that the albuminoids are 

 veritable nitryls of the amyloids; under which convenient term hi- includes 

 those hydrates of carbon which are susceptible of conversion into glucose. 

 (Ibid., May, 1860, p. 856.) 



In 1861, Messrs. Fischer and Boedeker announced the production of fer- 

 mentescible sugar by the action of dilute acids on cartilage, and showed that 

 the ingestion of gelatine increases the amount of sugar in normal human 

 urine. These authors seem, by the abstract before me (Repertoire de Chirnie 

 Pure, July, 1801, from Ann. der Chem. und Pharm., CXVII. ].. Ill), to 

 ignore alike my own observations and those of Gerhardt, who twenty years 

 since showed that, by long boiling with dilute sulphuric acid, there is formed 

 from gelatine a sweet fermentescible sugar, together with a large amount of 

 sulphate of ammonia, (Precis de Chirnie Organique, II. p. 621. ) 



