582 STEVENSON— FORMATION OF COAL BEDS. [November 3, 



crenic, humic and other organic acids. He was inclined to believe 

 that this material had been produced by the leaching out of soluble 

 salts of organic acids, in part crenates, from the upper part of the 

 bog and their concentration in the denser portions below, where they 

 filled cavities in the peat. The rapid change in color is not the 

 trifling change due to drying, but is a characteristic reaction of 

 crenic acid, due to oxidation and to partial change into apocrenic 

 acid — a feature observed in the acid and in its salts, both in nature 

 and in the laboratory. 



Lewis'^' described the material with more detail. It occurred in 

 swamp muck underlying 8 to 10 feet of peat. Near the bottom and 

 confined wholly to the muck, are irregular veins filled with a black 

 jelly-like elastic substance, in quantity varying from mere stains to 

 streaks, two or three inches wide. When first taken out it is jelly- 

 like, with conchoidal fracture, but on exposure it becomes tougher 

 and more elastic. Under the glass it is brownish red and nearly 

 homogeneous. It is tasteless and odorless, burning slowly and with- 

 out flame, when fresh. It is insoluble in water, alcohol and ether 

 but is dissolved by caustic potash. Completely dried, it is brittle 

 and coal-like, resembling jet ; it burns with a clear yellow flame and 

 no longer softens in water. In composition, it difl^ers from the 

 typical dopplerite in that it contains little more than half as much 

 carbon and very much more oxygen. 



Kaufmann, cited by Lewis, regarded dopplerite as a mixture of 

 humus acids and believed that the portion of peat, soluble in caustic 

 potash, is identical with dopplerite. Compact peat contains minute 

 black particles of dopplerite. Peat is merely a mixture of partly 

 decomposed plants with dopplerite, the latter being a homogeneous 

 peat in which all organisms have been decomposed. Kaufmann 

 found that the proportion of material soluble in caustic potash in- 

 creases with age, a recent peat giving from 25 to 30 per cent., while 

 an old compact peat gave "JJ per cent. But in coals, the proportion 

 decreases, from a diluvial brown coal, with yj per cent., to anthracite 

 in which no portion is soluble. His conception is that, in the forma- 



" H. C. Lewis, " On a New Substance Resembling Dopplerite, from a 

 Peat Bog at Scranton," Proc. Amer. Phil. Soc. Vol. XX., 1881, p. 112. 



180 



