188 ECONOMIC GEOLOGY. [Pt. III. 



above, that the presence of a seam in one locality in the Lower 

 Damiidas is not sufficient evidence of its extension over the whole 

 area occupied by beds of the same horizon in that series, and although 

 it is possible that the beds of the Kaniganj series are continuous 

 over larger districts of country, there is no absolute proof that 

 they preserve their thickness and quality to any considerable dis- 

 tance. 



The quality of Kaniganj coal has at times been much disputed, 



although long since practically ascertained. One 

 Quality of coal. . . . , . 



opinion expressed concerning it is, that it consists 



of a mixture of anthracitic and bituminous coal. This is not correct ; 

 the coal is by no means anthracitic, nor is it richly bituminous, but 

 it belongs to a variety of non-coking bituminous coal, with a large 

 proportion both of volatile matter and ash, and the apparent mixture 

 of different kinds of coal is caused by its being invariably composed 

 of lamina? of varying thickness, and consisting alternately of a bright 

 jetty black substance, and of a dull lustreless rock. The brighter por- 

 tions consist of a very pure coal, a sample of which from Sirsol mine 

 gave the following results on assay* : — 



Volatile ... ... ... ... ... ... 40- 



Fixed Carbon ... ... ... ... ... 57-5 



Ash 25 



This is the composition of some bituminous coals, but contains 

 rather more volatile gases than those best adapted for the production 

 of coke. But there can be but little doubt that, if a seam were disco- 

 vered, the whole of which showed the above proportions of carbon 

 and ash, a very fair coke indeed could be made from it. An inferior 

 coke may indeed be made from picked specimens of the coal from 

 some of the mines now at work, where the proportion of the bright 

 jetty black layers is large. 



* This and the following two analyses are by Mr. A. Tween. 



