60 



mallet: geology of darjiling and western duars. 



Of the coals mentioned at p. 54, the Tindharia, which contains 

 about 12 per cent, of volatile matter, and which cakes slightly in the 

 open fire, yields a firm hard coke when the powder is ignited in a covered 

 crucible. Coal from the Rakti and Pankabari seams does not coke at all, 

 although the assay of the latter agrees closely with that of the Tindharia. 

 It is a well-known fact that the coking property of coal does not depend 

 solely on the percentage of volatile matter, although a certain amount of 

 such is indispensable. Much of the Darjiling coal is too near anthracite to 

 give promise of being convertible into a good coke, and the above experi- 

 ments seem to indicate that some of it will not coke at all. The follow- 

 ing table shows the amount of free carbon and ash, after the elimination 

 of the volatile matter, in the coals mentioned at p. 54. 





.Carbon. 



Ash. 



Rakti naddi 



... 5' 



6" 



seam 



858 



142 



Cart road 



... 6' 



0" 



» 



81-4 



186 



Chirankhola naddi 



... 7' 



0" 



» 



73-4 



266 



Tindharia ravine 



... 11' 



0" 



» 



75-7 



24-3 



Ravine south of Pankabari .. 



... 0' 

 Average 



9' 



)> 



72-5 



27-5 , 





77-8 



22-2 



As artificial fuel the coal promises to turn out well. Mr. J. Grant 

 of Barakar, who has had the management of patent fuel works at 

 Raniganj, was kind enough to experiment on a few pounds of dust-coal 

 from the Rakti naddi 5' 6" seam. The ingredients used were in the 

 following proportions : — 



Dust-coal 



Starch, composed of -< 



( Flour 

 Water 



Crude carbolic acid 



] ton. 

 12 to 16 lbs. 

 30 to 35 gals. 



1 pint. 



( 60 ) 



