2/0 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 14, 



Analysis of American Coals and Coke, dried at 250° Fahr. 

 Moisture 1 to 1 J per cent. 



Carbon 



Hydrogen ... 

 Oxygen an d1 

 Nitrogen J 

 Ash 



Coal and Coke of the Newer Coal-field of Eastern Virginia. 



Ancient Coal 

 of Alabama. 



Coal, 

 Clover-hill. 



Coal, 

 Blackheath. 



Coal, 

 Deep-run. 



Coke — Townes 

 and Powell's. 



Coal, 

 Tuscaloosa. 



76-49 

 5-23 



841 



9-87 



80-38 

 4-08 



619 



9-35 



82-90 



4-77 



5-97 

 6-36 



86-54 

 4-23 



4-53 



4-70 



80-96 

 5-13 



7-83 



6-08 





100-00 



100-00 



10000 



10000 



100-00 



Clover-hill, Blackheath, and the Deep-run mines respectively, represent 

 the southern, middle, and northern parts of the coal-field treated of in 

 this memoir. On comparing this analysis of the Clover-hill coal as 

 here given, with Dr. Percy's analysis of the older coal from Pomeroy 

 on the Ohio (see this Journal, vol. i. p. 199, May 1844), we cannot 

 but be struck with the identity of the results, as far as relates to the 

 proportions of carbon and hydrogen. Thus the ancient coal of 

 Pomeroy gave, carbon 76 "70, hydrogen 5*67, in which it will be seen 

 that the figures are the same, except the decimals, as in the analysis 

 of the newer coal from Clover-hill. Nearly the same remarks are 

 applicable when we compare the Blackheath coal and that of Tusca- 

 loosa in the annexed table. 



. That there should be a disengagement of inflammable gas from this 

 coal, containing so much volatile matter, was to be expected ; accord- 

 ingly, in spite of the usual precautions taken to prevent accidents, 

 ^several fatal explosions have occurred ; one of these happened at 

 Blackheath in the old pit in 1839, by which forty-five negroes and 

 two white overseers lost their lives. They were killed, not by choke 

 damp, but by the combustion of carburetted hydrogen, attributed by 

 the miners to the spontaneous ignition of coal mixed with decomposing 

 pyrites. The most approved methods of ventilating the mines had 

 been introduced, but another terrible accident occurred so late as the 

 year 1 844, at the depth of more than 900 feet, at Blackheath, occa- 

 sioned by the leaking out of gas from some deserted works, which 

 had been ineffectually dammed off from the new galleries. 



On Beds of Coke and Altered Coal, and the Action of Intrusive 

 Igneous Rocks. 



Although rocks of volcanic origin do not form a prominent feature 

 in the geological structure of this coal-field, as they do in the region of 

 the new red sandstone of Connecticut and New Jersey, they are not 

 wanting, and I shall next describe the manner of their interference 

 with the strata and the changes they cause at and near their contact. 



At the southern extremity of the coal-field at Clover-hill before 

 alluded to, four miles north of the Appomattox River on " Johnson's 



