380 GEOLOGY OF THE DENVEK BASIN. 



been obtained in the West, on account of the difference in barometric 

 pressures. The specific gravities can not be considered in reference to the 

 moisture contents of the coals, for the former determinations are invariably 

 made upon saturated particles, which would, therefore, evidently present like 

 conditions for determination in both localities. 



An explanation of the inter-relations of the volatile-combustible and 

 water contents of the coal may possibly be found in a striking peculiarity 

 displayed by certain coals, of quickly taking up a large per cent of water 

 under a moist condition of the atmosphere and of as readily parting with 

 it under a drier condition. 1 The discovery of this peculiarity was made in 

 1884 in the course of investigations conducted at Newport, R. I., upon an 

 anthracite from that State and upon a lignite from the Mouse River region 

 in Dakota. In the case of the anthracite, upon which the investigations 

 were more extended, the variation in the contents of water amounted to 

 from 10 to 15 per cent, according to the hygrometric conditions of the 

 atmosphere, one series of analyses being made during prevailing north 

 and west winds, conducive to dry atmosphere, the other during southwest 

 winds, which in Newport are frequently accompanied by too-. A piece of 

 Pennsylvania anthracite, and also bituminous coals from the Cumberland 

 held and from Montana, however, exhibited no such features. 



Although a similar explanation of the difference in the water contents 

 of the coals of the Denver iield is possible, it is not altogether satisfactory, 

 since it involves the reverse of the usual conditions of moisture and dry- 

 ness in the East and \Vest. In this instance there appears a considerable 

 increase in the per cent of water in the coals analyzed in the dry atmosphere 

 of the West over that of the determinations made in Washington. 



The lapse of time between the sampling ami analysis of the above 

 coals probably had little or nothing to do with the hygroscopic peculiarities 

 exhibited, for both in the East and the West this interval, in some cases, 

 extended over a period of several months, more than ample for the full 

 exertion of the phenomenon, since, in the special cases referred to above, 

 both absorption and elimination of moisture were rapid, and practically 

 reached their limits within twenty-four to eighty-five hours after exposure. 



Notes on Rhode Island and Massachusetts coals, Arthur B. Emmons: Trans. Am. Inst. Mill. 

 Eng., Vol. XIII. Sept., 1884, p. 510. Also Water in coals: idem, Vol. V, Ju»e, 1876, pp. 97-99. 



