THE SCIENTIFIC PERIOD 15 



advantage as compared with their German brethren, in that they were 

 obliged to travel to foreign countries to study large mines, whereas the 

 German schools were all situated in the midst of important mining dis- 

 tricts. On the other hand, while the German displays great industry 

 and acuteness of observation in his collection of facts, the Frenchman 

 has a remarkable faculty of logically grouping them and of clearly and 

 concisely stating the conclusions to be drawn therefrom. The French 

 language, moreover, by its structure is much better adapted to a concise 

 presentation of scientific concepts that are readily understood by the 

 reader than the German, which is likely to be involved and cumber- 

 some in its mode of expression. Hence, toward the middle of the cent- 

 ury the influence of the French geologists on genetic speculation became 

 predominant, especially as it was based on synthetic experiment, a branch 

 of geological investigation which for a time they practically monopolized. 

 The first of the French geologists who has left an enduring impress 

 upon the theory of ore deposits was Elie de Beaumont, who for nearly 

 fifty years occupied the chair of geology at the Paris School of Mines 

 (1827-1874). In 1847 he published, as an abstract of his lectures, his 

 well-known paper " Volcanic and metalliferous emanations," in which 

 he does not claim to formulate a complete or final theory, but presents his 

 views as explanations which seemed to him best to fit the facts of nature 

 as then known. His conclusions are, briefly : That the metallic minerals 

 in veins of incrustation (since called crustification) find their ultimate 

 source in eruptive rocks, from which they emanate at first in gaseous 

 form. As they pass through long canals or fissures, at greater distances 

 from the center of eruption they must condense and thus form deposits 

 analogous to those of springs at their point of exit. The metals in veins 

 are found united less frequently with oxygen than with certain elements 

 to which the name " mineralizers " has been given, and which are not 

 only volatile themselves, but possess the property of rendering volatile 

 many substances with which they combine. These are sulphur, selenium, 

 arsenic, antimony, phosphorus, tellurium, chlorine, bromine, and iodine, 

 etcetera. 



Mineral •springs he divides into principal or hottest thermals, which 

 are fed by gases emanating directly from eruptive masses whicji reach 

 the surface in a fluid state, and, second, less heated springs, which often 

 accompan}^ the former. The latter are fed by meteoric waters, which 

 descend until they come in contact with hot rocks and, when heated, 

 ascend again, in which journey they may be charged with mineral 

 substances. 



Vein deposits may be formed by either class of thermals ; the second 

 class would form deposits not only in ordinary fissures, but also in those 



