SEVENTH ANNUAL MEETING 



107 



Table I. 



PROXIMATE ANALYSES OF MINERAL CHARCOAL AND OF AVERAGE 

 COAL FROM THE SAME SEAMS 

 (a) Charcoal samples; (b) Average. 



Nos. 1-8. Analyses by McCreath, second Geological Survey of 

 Pennsylvania. Vol. MM, pp. 1-107; Moisture at 225 degrees F. 



No. 9, Analyses 111. Geol. Survey, Herrin (No. 6) coal, William- 

 son County, Illinois; Moisture air dried. 



that settled over the coal basin during the long period of ac- 

 cumulation of the vegetable matter. The amount of ash in a 

 coal bed varies very considerably at different levels and in 

 different places even in the same mine. Among the possible 

 causes of such variation are differences in the proportions of 

 the kinds of plants that formed the coal, removal and deposi- 

 tion of mineral matter by ground water, and wind-blown dust. 

 Hence, in the absence of definite evidence of sediment con- 

 tributed by water, such as black shale or mud partings, it is 

 thought that, as far as the bearing on the conditions of ac- 

 cumulation of the vegetable matter is concerned, not much sig- 

 nificance can be attached to the variation in the amount of ash 

 in a coal bed of a small percentage above or below the original 

 amount that may have come from the plants that formed the 

 coal. 



