142 STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS 



ence will be made in another connection. Raefler,^^^ opposing the 

 doctrine, examined closely most of the mines in the Sachsen area. 

 Extended reference to this work will be made in discussion of the 

 doctrine of Potonie. The plates illustrate well the lens-like form of 

 the brown coals, showing isolation of the several portions of the beds 

 and suggesting that the lenses were not wholly contemporaneous. 

 The rudely crescent forms observed in cross-sections of the lenses 

 with depressed upper surface make clear the effect of compression on 

 the thick mass of vegetable matter midway in the little trough. 

 Several of his profiles indicate " Sandsacke " filled with " glazial 

 Diluvium." The coal is very little disturbed in many places but in 

 others the plications are very close. Some of these are evidently pre- 

 glacial and the erosion was extreme ; but it does not seem to have 

 been contemporaneous in any case. 



Pyropissite occurs in some portions of the Sachsen area. It is 

 described by Zincken as amorphous, earthy, with earthy fracture ; it 

 is gray to yellowish to white, greasy to gummy feel and fuses to an 

 asphaltic mass ; it passes into Schwelkohle, a mixture of pyropissite 

 and ordinary brown coal. Here only the geological relations may be 

 considered; other matters belong under chemistry as of the brown 

 coals. 



Stohr,-"" in the memoir already cited, states that in southern 

 Sachsen pyropissite is an integral part of the coal bed. The pure 

 mineral yields 40 to 50 pounds of tar to the ton, from which paraffin 

 and mineral oil are obtained ; Hhe ordinary material yields only 20 

 to 25 pounds. Until recently, the Schwelkohle was thought to be 

 worthless and of rare occurrence; but, though absent from most of 

 the area, it is present at many localities. It is not always a distinct 

 bench, but at times forms laminse in the upper part of the Feuer- or 

 fuel coal. The distribution seems to be lens-like, for Stohr refers to 

 nests of Schwelkohle. A variable layer of Russkohle intervenes 

 between the Schwelkohle and the roof, ordinarily not more than 

 6 inches thick, but at one stripping he found this layer from 2 to 3 

 feet. He summarized his observations thus : 



193 F. Raefler, " Die Entstehung der Braunkohlen lager zwischen Alten- 

 burg und Weissenfels," Inauguration Dissertation, Jena, 191 1. 

 200 E. Stohr, Neucs Jahrbuch, 1867, pp. 410-424. 



