Excerpt from Contributions to the Study of Coal: Influence of Structural Irregularities Upon the Chemical Character of No. 6 Coal in Franklin and Williamson Counties, Illinois; Distribution of Sulfur in Illinois Coals and Its Geological Implications Within the large area of the Illinois coal basin, the rank of coals varies through almost the entire range of the high-volatile group, in general increasing southward or southeastward across the basin. The rate of variation within the greater part of the area is so gradual that the chemical character of any bed is well represented by average values for fairly large areas, such, for example, as are represented by individual counties. This is particularly true of the calorific value for the dry, mineral matter-free coal - what has been designated the unit coal calorific value. County average unit coal values have for several years been recommended by the State Geological Survey as generally applicable to the coal in individual mines in any county. It has been known for some time, however, that the rate of varia tion in rank is considerably more rapid across the counties lying along the southern margin of the coal basin than across the counties to the north, so that in Franklin, Williamson, Jackson, Saline and Gallatin counties, analyses of individual samples are likely to vary more from county averages than is the case north of the border belt. Inasmuch as structural conditions affecting the coal beds are more irregular in this marginal belt than elsewhere in the State it has been suspected that variations in the chemical character of the coal, indicative of varia tions in rank, would eventually, with the accumulation of sufficient analytical and structural data, be found definitely related to structural irregularities. It was also realized that the discovery of such relation ships would probably necessitate the eventual abandonment oi county average values as the basis for standardization and the adoption cf values based upon the character of the coal bed within more natural structural units. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.