STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 177 



says that the poorer the coal is in benzol extract, the richer it is in 

 resin. " Bitumen " from pyropissite contains no resin soluble in 

 ether, but that from bitumen-poor coal may contain 25 per cent. 



Bredlick-'*^ states that Schwelkohle, when dried, resembles an 

 earthy brown coal soaked in a wax-like bitumen. It is not homo- 

 geneous but consists of layers of richly bituminous lignite. It fuses 

 at 150° to 200° C, thereby differing from fuel coal, which is in- 

 fusible. He cites Riebeck on composition of pyropissite, which, ash- 

 free, is carbon, 73.48, hydrogen, 11.70, oxygen, 14.80, while the 

 associated fuel coal, according to Bredlick's analysis, has carbon, 

 64.78, hydrogen, 5.65, oxygen and nitrogen, 29.56. The several 

 substances, when subjected to destructive distillation, yield 



Gas begins to pass off from pyropissite at 120° C. to 150° C, 

 and the maximum temperature reached in the process is 640° C. The 

 tar is of butterlike consistence when cooled, has gravity of 0.85 to 

 0.91, consists chiefly of paraffins and olefins, there being only traces 

 of benzol and its homologues. This tar is fractioned and yields a 

 paraffin free oil and paraffin wax, with a residuum. The last, about 

 one third of the whole, is placed in another retort and heated to 

 beyond the " cracking point." The gas from Schwelkohle is in- 

 ferior; according to Graefe, its composition is: Carbon dioxide, 10.9; 

 heavy hydrocarbons, i.i ; oxygen, 6.3; carbon monoxide, 8.5; 

 hydrogen, 22.6; carburetted hydrogen, 6.4; ethane, 2.0; nitrogen, 

 42.2. The candle-power is from 8 to 12. 



The Blatterkohle or Dysodil, which is a Tertiary Lebertorf, has 

 been found in Sicily, France, Bohemia and other countries, but the 

 most important deposits are near the Rhine in the Siebengebirge. 

 The composition of material from Westerburg, according to Cassel- 

 mann,^*® is: Carbon, 62.80; hydrogen, 6.76; oxygen and nitrogen, 



245 W. Bredlick in " Fuels Used in Texas," Bull. Univ. Texas, 307, 1913, 

 pp. 169-178. 



246 Cited by C. F. Zincken, p. 180. 



