19".] STEVENSON— FORMATION OF COAL BEDS. 583 



tion of coal from peat, the first step is the formation of dopplerite 

 and the second is a gradual transformation of the latter into a mate- 

 rial less soluble in alkalies and richer in carbon. The peculiarities 

 of the Scranton mineral, its low percentage of carbon and its mode 

 of combustion led Lewis to suggest that it may represent an earlier 

 stage in transformation than that of dopplerite. 



V. Giimbeh** in giving the results of his later studies, described 

 dopplerite as a yellow brown homogeneous mass without trace of 

 organic structure and enclosing only separated parts of plants. It 

 burns with a sooty flame, thus difl:'ering from the Scranton mineral 

 which burns with a clear flame. It dissolves in acid with efferves- 

 cence ; the calcareous matter seems to be combined chemically with 

 the humus-like material. He is inclined to see in dopplerite a sub- 

 stance originating in mere segregation from plant material as the 

 silica of flints is separated from limestone. He looks upon dop- 

 plerite as possessing great importance, since in most peats, one finds 

 cementing substances which, optically, physically and chemicallv, 

 resemble it closely. 



Fruh,^** in his earlier work, already cited, gives an elaborate dis- 

 cussion and reaches conclusions differing very much in some respects 

 from those just given. He asserts that dopplerite exhibits the 

 wholesale formation of ulmin compounds and gives detailed descrip- 

 tion of its physical and chemical properties to prove that it belongs 

 to the ulmin group. Owing to the large proportion of calcium, he 

 thinks the material pre-eminently a Rasenmoor deposit. On wholly 

 fresh profiles of Rasenmoor at Gonten, Schwantenau and Rothen- 

 thurm, he saw in the red-brown peat, brown flakes, one centimeter 

 to one decimeter, so mottling the mass that he termed this type 

 Marmortorf. \^ery frequently the flakes are associated with a frag- 

 ment of root or twig, along which water would flow. At Rothen- 

 thurm he found the dopplerite first along a root. These brown 

 flocks are always rich in water ; the Rasenmoor is always rich in 

 water, a condition which favors homogeneous ulminification of the 



*S'. Giimbel, op. cit., pp. I2g, 130. 



'"J. J. Friih, op. cit., pp. 64, 68, 69-72. 



I'ROC. AMER. PHIL. SOC. , I,. 202 MM, PRINTED NOV. 1 6, I9II. 



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