COAL. 



385 



fine partings. The amount will very probably decrease in depth. The 

 ash of the Scranton coal is about that of many prairie lignites. 



The fuel ratio v c c . — Tliis is, at the present tiiiH\ the accepted basis of 

 classification of coals in the United States. The average of the early fuel 

 ratios of the Erie-Canfield region, the Lafayette-Louisville older mines, 

 and the Marshall district is 1.33; that for the shallow mines of the foothill 

 region, including two at Golden, is 1.07; excluding the Golden region, 

 1.04; this, however, would be raised to 1.13 if the analyses of the coals 

 from the lower levels of the Old White Ash mine were included, the fuel 

 ratio of these being 1.25 — well up toward the ratios of the prairie coals, and 

 again showing the transition in depth of the vertical coals to the composi- 

 tion normal for the undisturbed coals of the prairies. The fuel ratio of 

 the Scranton coal is that of a typical lignite, 0.96. 



CLASSIFICATION OF THE COALS. 



The coals of the Denver Basin may be classified as shown in the 

 following table: 



Table III. — Classification of the coals of the Denver Basin. 



based upon the ratio — — , the coals of the Denver field fall into three 

 distinct classes, each of which is confined to a certain portion of the field 

 as at present developed, and, moreover, has for that portion a remarkable 

 uniformity of chemical composition. "Were it possible to make the correc- 

 tions which are unquestionably required for the more recent analyses, the 

 coals affording these would in all probability likewise fall into one or another 

 of the three classes established upon the earlier analyses! 



3ION XXVII 25 



