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had been poured out, at different times, through a fissure, and 

 spread over the materials of the sandstone and conglomerate at 

 the bottom of the sea, thus producing ahernating beds of these 

 rocks. In the bed of Eagle River, below the Phcenix Mines, Dr. 

 Jackson's Assistant, Mr. George O. Barnes, had found no less than 

 eleven distinct beds of sandstone and conglomerate alternating 

 with the trap ; and Dr. Jackson had previously described six of 

 those alternations in his notes of the survey of the mining district 

 of Copper Falls. It is true that there are cupriferous beds 

 running with the " country," or parallel to the trend of the 

 trappean range, and of the sandstone strata, which have a course 

 E. N. E., and W. S. W., and that there are also crossing veins, 

 which traverse these at right angles, and are generally rich in 

 metallic lodes, and have well-defined walls and vein stones well 

 characterized, Prehnite being the most common of the outcrop- 

 ping wall stone of the native copper veins, though Leonhardite, 

 Laumonite, and Calcareous Spar, also occur in a similar manner 

 in the mines ; while Analcime, Apophyllite, Mesotype, and 

 Chabasie, are common accompanying minerals. Toward the 

 Ontanagon, and also in Isle Royale, Epidote is the most common 

 vein stone, and even forms large beds filled with small irregular 

 grains of copper, which often amount to eight per cent, of the 

 mass. It is a curious and interesting fact that, although a vein 

 fissure traverses both sandstone and trap-rocks, the only metal- 

 liferous portion of the vein is that which traverses the trap. 

 This, Dr. Jackson explained as the result of the chemical action 

 of protoxide of iron in the trap-rock, which decomposed the 

 vapor of chloride of copper, as it rushed from the interior of the 

 earth through the crevices ; if, as is probable, these wonderful 

 native copper lodes, are the products of sublimation and of 

 galvanic segregation of the metal from vapor. 



The Corresponding Secretary announced the reception 

 of the following letters, viz : — 



From the Royal Institution, Oct. 12, 1855, and the Royal 

 Geographical Society, Nov. 14, 1855, returning thanks for copies 

 of the Journal and Proceedings ; from the Zoological Society of 



