coal. 379 



considerably below that of other coals of adjoining or nearly related 

 areas which were earlier sampled and analyzed in Denver, the difference 

 amounting to between .'i and 5 per cent. At the same time the volatile- 

 combustible matters are found to vary in the opposite direction, increasing 



in their per cents approximately as much as the water contents decrease. 

 The specific gravities also vary inversely as the water contents and directly 

 as the volatile-combustible matters. 



At present it is impossible to suggest any satisfactory explanation of 

 the above peculiarities. Such results were not anticipated, and, moreover, 

 are not only opposed to what would be expected from physical laws, but are 

 apparently opposed to one another. For instance, the natural inference 

 based upon the hygroscopicity of coals would have been that the analyses 

 in the very moist atmosphere of Washington as compared with the very 

 dry one of Denver would have given the higher per cent of water at the 

 former place, [nstead of this, the coals analyzed at Denver parted with 

 a much larger amount of moisture, notwithstanding many of the samples 

 were exposed to the dry climate of the region for two or three months 

 before analysis — a length of time ample to bring them to a stationary 

 condition in the quantity of their water contents. 



It would seem hardly possible that the volatile-combustible matters 

 could be influenced either one way or the other by altitude above sea- 

 level or the condition of the atmosphere. There is, however, a variation 

 inversely as the water. So persistent is this in the coals from the various 

 localities that it is highly probable that the figures of this column are 

 directly dependent upon those of the water column, a possible inference 

 being that in the Denver analyses some of the volatile matters may have 

 escaped in the moisture determination, although the analyses were made 

 in the same manner, by the same chemist, with the same care, and at the 

 same temperature, it is a significant fact that the sum of the volatile- 

 combustible and moisture contents is approximately the same for both 

 suites of analyses — Washington and Denver. 



Again, the specific gravities of the coals determined in Washington 

 are considerably higher than those determined in the West. Under 

 precisely similar conditions of manipulation, the higher results should have 



