60 Ball Coal of the Burdwan Mines. [Jan. 



found very tough and difficult to cut with a saw. There was no differ- 

 ence between the centre and the periphery of the ball, nor any thing 

 that could give the idea of a nucleus or of concentric layers. 



And upon considering it attentively it will be seen at once that it is 

 nothing more than an oblique rhomboidal prism of the common coal 

 of the mines, rounded somehow into a rough ball. So far, for the present 

 as to its external characters. 



I find its specific gravity to be 1.37. The mean of 5 specimens* of 

 Burdwan Coal is 1.365. I place here its analysis and the mean of the 

 first six specimens referred to in the note below. 



Analysis of the Ball Coal. Mean of Burdwan Coal. 



Mr. Prinsep i s Table. 



Water, 5.00 7.4. 



Volatile matter, 29.00 35.6. 



Carbon, 57-00 52.5. 



Ash, 9.00 12.2. 



100.00. 



There was a slight excess in my analysis ; no doubt due to the 

 peroxidation of the Iron. 



I had not, from Mr. Williams, any note of the particular mine from 

 whence our ball was taken, so as to compare its analysis with that 

 particular coal, but from its agreeing so nearly, we can have little doubt 

 of its having the same origin as the average of Burdwan Coals. But 

 then comes the curious question of " How did it become rounded and 

 deposited in the coal bed after it was a rhomboid of coal? for the 

 total absence of any concentric layers or other trace or indication of 

 organisation, leaves no doubt about its having been one. It is in fact 

 such a rounded boulder of somewhat tough coal as we should expect 

 to meet with in a stream of moderate velocity — with its layers parallel 

 to the base of the prism. 



I fear this must remain, like so many other geological questions, 

 matter of conjecture ; for the imagination is almost startled at the idea of 

 the time required for coal to be formed, and then broken up and carried 

 off in boulders to be deposited again in new beds forming at a distance : 

 as we might suppose the Mississippi to be now rolling lumps of coal 

 with its huge rafts of timber and mighty masses of vegetable matter, 

 * From the first six in Mr. Prinsep's Table; Journal, Vol. VII. p. 197. 



