8i6 THE POPULAR SCIENCE MONTHLY. 



According to recent investigations, the almost boiling Steamboat 

 Springs in the United States precipitate, besides sulphur, small quanti- 

 ties of gold, mercury, silver, lead, copper, and zinc, which, by the aid 

 of certain salts and their high temperature, they hold in solution. 

 These deposits appear to be the continuation of those which in the same 

 region, as at Sulphur-bank, have formed beds which are mined for 

 their mercury. 



"What we have been able to observe from the surface of the ground 

 gives a very limited and imperfect idea of the actions Avhich excava- 

 tions made to secure some particular thermal waters have revealed to 

 us. The bottom of the basin of the principal spring at Bourbonne-les- 

 Bains, where the temperature reaches 68° C, has furnished some very 

 remarkable facts relative to the formation of minerals. The place was 

 a flourishing station in the Roman period. In draining an ancient well 

 a blackish mud was reached which contained fragments of wood, 

 acorns, thousands of filberts which had become black like lignite, and 

 numerous medals. The washing of four cubic metres of the mud 

 yielded more than five thousand .pieces of money, mostly of bronze or 

 tin, but some of silver and gold. The four coins of the last metal bore 

 the images of Xero, Hadrian, Faustina the younger, and Honorius. 

 Twenty of the silver pieces belonged to the Gallico-Roman period, 

 while the other coins were consular or imperial pieces, mostly of the 

 first centuries of the empire ; but some were as recent as the Lower 

 Empire. The bronze pieces of the medium and smaller sorts were 

 likewise of different ages, but three types of Augustan coins predomi- 

 nated. ]\[any of them had been cut in two, doubtless to prevent their 

 being taken out and used again, they having been cast in as offerings 

 to the health-giving fountains. Ex-voto offerings were also recovered, 

 including a bronze statuette of a man Avhose leg had been hurt. 



Some of the coins had been so corroded by the action of the hot 

 water that the figure on them could not be discerned. Others had 

 been further corroded into holes and notches. ]\Iany others had been 

 wholly dissolved, but had engendered, at the exDcnse of their bronze, 

 new and solidly agglutinated combinations. The species thus origi- 

 nated were identical in their crystalline forms and general characters 

 with similar natural minerals — sulphuret of copper, copper pyrites, and 

 variegated copper-ore. The most numerous crystals are regular tetra- 

 hedrons, like those of the mineral called gray antimonial copper, of 

 which they have also the composition, the luster, and other properties. 

 In some of the coins the tin of the bronze has passed into the state of an 

 oxide, and has formed a white superficial crust. A real separation has 

 therefore been produced between the metals of the alloy by the differ- 

 ent workings of their chemical affinities. It seems as if in all of these 

 transformations Nature, claiming her rights upon what human industry 

 had taken out of her domain, had been pleased, with the aid of the 

 mineral water, to recover her property, and reconstitute exactly the 



