46 J. J. STEVENSON — PENNSYLVANIA ANTHRACITE. 



The coal-beds of the upper division are thin and variable, but one, 

 near the bottom, is mined at many localities between the state line at 

 the west and Johnson county at the east. The Intermediate division is 

 practically barren, though occasionally a bed develops into local impor- 

 tance. One opening in northeast Franklin county yields a coal whose 

 composition is not without interest in a discussion of some hypotheses. 

 The Lower division contains a persistent bed near the bottom which is 

 mined in Johnson and Pope counties. 



Dr. Owen gives results of analyses of coals collected by him, but they 

 differ so radically from those obtained by Professor Brackett for the 

 recent Geological Survey of Arkansas and given in Mr Winslow's report 

 that the two series cannot be compared.* 



The results of analyses presented by Mr Winslow are instructive in 

 view of some theories which have been offered to account for the varia- 

 tion in volatile in the coals of Pennsylvania and elsewhere, and reference 

 to them will be made more than once in the pages to follow. The dis- 

 tance from the state line to the last mine at the east, represented in the 

 analyses, is not more than 64 miles, and there is an intermediate space 

 of nearly 26 miles between the first group of analyses near the state line 

 and the second group in the more easterly counties ; yet the illustration 

 suffices for the purposes of this discussion. Arranged in geographical 

 order, the results show — 



First. That the coal of the upper division contains more of volatile 

 combustible matter than does that of the lower division, even where the 

 localities are but little separated. 



Second. That, in a general way, the decrease in proportion of volatile 

 combustible is in an easterly direction. 



The latter statement must be made in this qualified manner. The 

 lowest percentage of volatile is in the eastern counties, but the decrease 

 in that direction is by no means regular. The analyses are numbered 

 from the highest volatile to the lowest, number 27 being the semi- 

 anthracite. I have arranged those w^hich are nearly on the same line 

 according to their geographic position, giving under each its approxi- 

 mate distance in miles east from the state line. 



Upper division : 



Numbers 4 12 19 1 16 8 14 15 3 18 



Miles 2 5 10 11 13 24 26 38 40 41 



Intermediate division : 



Number 5 



Miles 39 



* The difference must be due to the metnod of sampling. The remarkable purity of the Spadra 

 coal, as shown by the Owen analyses, suggests that only hand specimens were used, whereas the 

 results obtained by Professor Brackett indicate careful sampling. 



