640 THE POPULAR SCIENCE MONTHLY. 



which they can not have been deposited except by the interme- 

 diary action of water. 



These views, which the direct observation of Nature had sug- 

 gested to Elie de Beaumont, have been experimentally verified by 

 De Senarmont. Working with close tubes under pressure, and at 

 a temperature very much higher than that of boiling water, this 

 eminent observer succeeded in reproducing the minerals of the 

 veins from the most common substances — quartz, sulphate of ba- 

 ryta, fluor-spar, iron and copper pyrites, blende, sulj)huret of anti- 

 mony, glance, spathic iron, and carbonate of zinc ; all of which 

 laboratory-minerals, in a crystallized condition, quite resembled 

 the analogous natural minerals. The fact of the contemporaneous 

 formation of many of these, as exemplified in the basins of exist- 

 ing springs, as at Bourbonne-les-Bains, come later to confirm and 

 complete this demonstration. Deep fractures or faults, which so 

 numerously furrow the crust of the earth, have therefore endured 

 various destinies in the series of the ages. Some have remained 

 empty, or have been filled only with fragments detached from 

 their walls. Others have furnished a way of exit for fluid erup- 

 tive rocks, basalts and porphyries, for example ; and, finally, there 

 are those with which we are now concerned, which have served, 

 by the intervention of water, as channels for metalliferous ema- 

 nations. 



These emanations have not been borne exclusively into faults. 

 Sometimes they have filled interstices of irregular and various 

 forms, thus constituting ore-bearing masses, now adjoining erup- 

 tive rocks, as if they had followed them, now incased in stratified 

 beds. Whatever their forms, these masses are often in relation 

 with faults which have served as vents for emanations, partly 

 watery, from the interior of the earth. 



Among the metalliferous deposits of the last category, some, 

 still better than the veins, demonstrate the intervention of min- 

 eral or thermal waters. The masses of hydrated peroxide of iron, 

 frequent at Berry, where the Romans mined for them, and in 

 Pdrigord, Lorraine, Franche-Comtd, and other districts, have been 

 attributed, with much probability, to the presence of gaseous 

 springs, in which iron was dissolved as a bicarbonate. The form 

 of globules with concentric laminations, or pitholiths, which they 

 affect, strikingly resembles the little spheroids of carbonate of 

 lime that are deposited every day in the basin from which the 

 thermal springs of Carlsbad gush and whirl. At times we may 

 recognize clearly that solutions of peroxide of iron have acted 

 upon the limestone which they bathed, for they have gradually 

 corroded it. This chemical action has also been exercised on ani- 

 mal and vegetable matters. At many places in Alsace the min- 

 eral contains minute fibrous fragments consisting of woody rem- 



