hy Dr, T. Sterry Hunt. 253 



approximately represented by mixtures of hydrocarbons with ve- 

 getable fibre. The following results have been selected from a 

 great number of analyses by various chemists, and are for the 

 most part taken from Bischof's Chemical Geology^ (Vol. i. cap. 

 XV.) The nitrogen, which in most cases was included with the 

 oxygen in the analysis, has been disregarded, and the oxygen 

 and hydrogen for the sake of comparison, have been calculated 

 fbr twenty-four equivalents of carbon. 



1. Vegetable fibre or cellulose, C24H20O20 



2. Wood, mean composition, ^'i^^i^-S^x^'i^ 



3. Peat, (Vaux,) C ., H14.4O10 



4. do (Regnault,) C24HH.4O9.6 



5. Brown coal, (Schrotter,) C., H^4.30io'6 



6. do. do (Woskresensky,).C._, H^gOy.g 



■7. Lignite, (Vaux,) Cg H, 1.305.4 



8. do. passing into mineral resin, .(Regnault,) ^24111503.3 



9. Bituminous coal, do C)24Hi O3.3 



do do C24H10O1.7 



do do C24Hg.40i.2 



do do C24H8O0.9 



do (Kuhnert and Grager,)..C24H7.40i.3 



do. (mean comp.).. . .(Johnston) C2 H9O2 — O4 



15. Albert coal, (Wetherell,) ... .0 4Hig.90i.6 



16. Asphalt, Auvergne, C24H17.7O2.2 



17. do. Naples, C4H ,4.502 



18. do. Bastennes, C 4H1 0^.7 



19. Elastic bitumen, Derbyshire, (Johnston,) C24H_;20o.3 



20. Bitumen of Idria, C 2 4 Hg 



21. Petroleum and naphtha, • C24H24 



In the above table we see the transition from peat and brown 

 coal to lignite, and thence to bituminous coal. Prof. Johnston 

 from his experiments in various coals, including oannel from 

 Wigan, splint coal from Workington and caking coal from New- 

 castle, deduced the composition given in 14, in which with C2 4 H9 

 the oxygen varies from two to four equivalents. It will be 

 seen from a comparison of the infusible Albert coal with the 

 bitumens 16, 17 and 18, how gradual is the transition to the true 

 petroleums and naphthas, from which oxygen is absent. The as- 

 phalts also, as will be observed, differ very much in their compo- 

 sition, and though generally much richer in hydrogen than the 

 bituminous coals, the variety from Naples (IV) which is com- 

 pletely fusible at 140^ C., contains less hydrogen and more oxy- 



