110 



animals, we are almost authorized to infer that they derive it 

 from their ultimately vegetable food. He suggested that this 

 fluor of the Cannel coal may, nevertheless, have been derived by 

 volcanic agency, from subterranean sources, possibly by hydro- 

 fluoric acid, in the form of vapor, transmitted through the fis- 

 sures of the coal, reacting upon the calcareous matter which 

 occurs among the earthy substances of many coal seams. The 

 fluoride of calcium, thus generated, may have been formed either 

 within the substance of the coal, or, more probably, in the pas- 

 sage of the hydrofluoric acid vapor through underlying beds of 

 limestone, and have been afterwards sublimed into the crevices 

 of the coal bed. 



Dr. Charles T. Jackson read a paper on the Importance 

 of the Science and Art of Mining, which, he stated, held a 

 rank second in importance to that of agriculture only. He 

 said that it was his wish to call the attention of the public 

 to the real metallurgic resources of the country, but, at the 

 same time, to condemn absurd or unprincipled speculation, 

 which had very much interfered with and retarded a healthy 

 and profitable development of American mining operations. 



Dr. Jackson described some of the most important mines in the 

 country, and gave a particular account of the newly-discovered 

 copper and silver mines of Lake Superior, especially of those 

 belonging to the Lake Superior, Pittsburg and Isle Royal, and 

 Boston companies, which he had been employed to survey. 

 Through his researches, the importance of the silver veins had 

 first become known to the public ; and he doubled not that they 

 would, ultimately, become profitable to the companies owning 

 them, and valuable sources of revenue to the government and to 

 the people. 



The Lake Superior mining district is very remarkable, espe- 

 cially the deposits of the native metals in the trap rocks, and in the 

 adjacent calcareous spar veins, which traverse the conglomerate 

 rocks. The trap rocks form very long and broad dykes in the 

 conglomerate and red sandstone, and pursue a north-east and 

 south-west course, nearly parallel to the coast of Kewenaw 

 Point, and are supposed to extend to the St. Croix, a tributary of 



