cxii GENERAL SUMMARY OF SCIENTIFIC AND 



that the stone-filled cavities in the quartz of rocks like elvan 

 may have originated. Phillips lias further described in this 

 connection the deposits from a solfatara in California, where 

 a fissure, alternately filled with hot water and with vapors, 

 has uj^on its walls crystalline quartz overlaid by chalce- 

 dony and by a gelatinous silica, which dries to a mass like 

 chalcedony, and incloses a considerable portion of cinnabar. 

 This quartz, which is supposed to be formed by the crystal- 

 lization of the opaline silica, holds fluid-cavities with bub- 

 bles of varying size, as well as gas and vapor-cavities. 



In this connection the observations of Daubree are impor- 

 tant. The old Roman baths of Bourbonne-les-Bains, in the 

 department of the Haute Marne, in France, having been late- 

 ly opened for repairs, there was found in the mud at the 

 bottom of the well a very large number of medals, statuettes, 

 and ornaments in bronze, silver, and gold, ofl'erings in ancient 

 times to the genius of the place. Beneath there was a layer 

 of fragments of sandstone cemented together by crystalline 

 minerals, which were also found incrusting some of the med- 

 als. Among these were the various sulphuretted ores of 

 copper, chalcosine, covelline, phillipsite, chalcopyrite, and an- 

 timonial tetrahedrite all distinctly crystallized ; together 

 with crystals of quartz supposed to be contemporaneous in 

 origin with the sulphurets. A piece of lead was incrusted 

 with cubical cleavable galena and anglesite, and in other 

 parts of the deposit pyrite and crystals of calcite and cha- 

 bazite were met with, as in the well-known similar cases of 

 the thermal springs of Plombieres and Luxeuil. The waters 

 of Bourbonne, which rise through mesozoic strata, are strong- 

 ly saline, and contain alkaline and earthy sulphates and 

 chlorids. Their temperature is about 60 Centigrade ; and it 

 is clear that it is the action of these waters on the metals 

 during many centuries which has generated these crystalline 

 compounds, which present all the mineralogical characters of 

 the same mineral species fouud in the veins of Cornwall and 

 elsewhere. 



J. D. Dana has described the curious associations of miner- 

 als at the Tilly Foster iron-mine in Putnam County, N". Y. 

 The rocks are here hornblendic gneisses of Laurentian age, 

 including beds of magnetite mingled with chondrodite, 

 which is sometimes predominant. It is often associated 



