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SCIENCE. 



[N. S. Vol. XXIII. No. 575. 



very important part in the underground 

 economy. 



This general question has attracted more 

 attention in Europe in recent years as re- 

 gards hot springs than in America. So 

 many health resorts and watering-places are 

 located upon them that they are very impor- 

 tant foundations of local institutions and 

 profitable enterprises. Professor Suess, 

 whom I have earlier cited, delivered an ad- 

 dress a few years ago at an anniversary 

 celebration in Carlsbad, Bohemia, in which 

 he maintained that in the Carlsbad dis- 

 trict the natural catchment basin was in- 

 sufficient to supply the waters and that both 

 the unvarying composition and amount 

 through wet seasons and dry were opposed 

 to a meteoric source. Water, therefore, 

 from subterranean igneous rocks, well- 

 known to exist in the locality, was be- 

 lieved to be the source of the- springs. The 

 same general line of investigation has led 

 Dr. Rudolf Delkeskamp, of Giessen, and 

 other observers to similar conclusions for 

 additional springs, so that magmatic waters 

 have assumed a prominence in this respect 

 which leaves little doubt as to their actual 

 development and importance. 



All familiar with western and south- 

 western mining regions know as a matter 

 of experience, that the metalliferous veins 

 are almost always associated with intrusive 

 rocks, and that in very many cases the 

 period of ore formation can be shown to 

 have followed hard upon the entrance of 

 the eruptive. The conclusion has, there- 

 fore, been natural and inevitable that the 

 magmatic waters have been, if not the sole 

 vehicle of introduction, yet the preponder- 

 ating one. 



With regard to their emission from the 

 cooling and crystallizing mass of molten 

 material we are not, perhaps, entirely clear 

 or well established in our thought. So long 

 as the mass is at high temperatures the 

 M'ater is potentially present as dissociated 



hydrogen and oxygen. We are not well 

 informed as to just what is the chemical 

 behavior of these gases with regard to the 

 elements of the metallic minerals. Hydro- 

 chloric acid gas is certainly a widely dis- 

 tributed associate. If, as seems probable, 

 these gases can serve alone or with other 

 elements as vehicles for the removal of the 

 constituents of the ores and the gangue, 

 the possibilities of ubiquitous egress are 

 best while the igneous rock is entirely or 

 largely molten. In part even the phe- 

 nomena of crystallization of the rock-form- 

 ing minerals themselves may be occasioned 

 by the loss of the dissolved gases. Through 

 molten and still fluid rock the gases might 

 bubble outward if the pressure were insuf- 

 ficient to restrain them and would, were 

 their chemical powers sufficient, have op- 

 portunity to take up even sparsely dis- 

 tributed metals. 



On the other hand, if their emission as 

 seems more probable, is in largest part a 

 function of the stage of solidification and 

 takes place gradually while the mass is 

 congealing, or soon thereafter, then they 

 must depart along crevices and openings 

 whose ratio to the entire mass would be 

 similar to those given above. They might 

 have, and probably do have, an enhanced 

 ability to dissolve out in a searching and 

 thorough manner the finely distributed 

 metallic particles as compared with rela- 

 tively cold meteoric waters which might 

 later permeate the rock; but as regards 

 fhe problem of leaching, the general rela- 

 tions of crevices to mass are much the 

 same for both, and it holds also true that 

 the discovery of the metals by assay of 

 igneous rocks proVes that all the original 

 contents have not been taken, by either 

 process. 



AA^'e may, however, consider an igneous 

 mass of rock as the source of the water 

 even if not of the ores and gangue, and 

 then we have a well-established resei-voir 



