STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 37 



others. The Upper Trias coals of Austria are usually caking and 

 those of the Richmond area are always so. Apparently no relation 

 exists between proximate composition and tendency to cake. 



No reference to the presence of resins in coals of the Jura or 

 Trias is made in any of the works to which the writer has had 

 access. One observation by Witham, cited by Miller, bears upon the 

 subject. In studying silicified stems of Piniis eiggensis from the 

 Lower Oolite of Scotland, he discovered that the wood abounds in 

 turpentine vessels or lacunae, well defined and varying in size. 



Mineral charcoal (Fusain, Faserkohle) is a characteristic fea- 

 ture throughout. At times, it forms thin partings in seams, but at 

 others it is an important constituent of thicker partings, where its 

 abundance suggests that the partings are merely residues from a 

 considerable mass of peat. Occasionally it is in lumps, embedded 

 in the coal or in a clay parting. 



Sphserosiderite or clay ironstone is reported by all except a very 

 few observers. It is present in the coal, in the underclays, and is 

 scattered in the other rocks, while occasionally it is in layers of 

 varying thickness. At times, it replaces the stems of trees or frag- 

 ments of wood. Black band layers, associated with seams of coal, 

 have been reported from the Ipswich formation of Queensland and 

 from the Rhastic of North Carolina. 



The Jurassic coals of Great Britain are lignite or very low grade 

 bituminous. No analysis of the coals in France is available. The 

 analyses of the Austrian coals, as officially given, are incomplete 

 and afford no information for comparisons ; but the coals are clearly 

 high grade bituminous, for that of many seams is caking. Hantken 

 has published many analyses of the Jurassic coals in the Steierdorf- 

 Anina and Fiinfkirchen areas, and Nendtwich made a number at 

 a much earlier date. The Steierdorf-Anina samples have as proxi- 

 mate composition : 



The low percentage of ash makes evident that the analyses are 

 of specimens supposed to represent the average best coal from the 

 mines. This, however, is unimportant here. The upper Liegendflotz 

 is separated from the higher bed by about 300 feet of rock. No 

 marked tendency to decrease of volatile downward is recognizable 



