No. 2.] SPENCER — COPPER-MINING. 79 



The large masses of copper are usually detached in the 

 mines by blowing down all the surrounding rock, after which 

 they are cut up into portable masses of 4 to 7 tons, by 

 means of chisels less than an inch wide, making long grooves 

 through the masses, after which they are brought to the surface 

 and the attached pieces of rock are removed as far as practicable. 

 The masses of copper together with the concentrated mineral 

 are smelted alone in reverberatory furnaces (of which there are 

 seven) at Portage Lake or in Detroit. The slag rich in copper 

 is again smelted with lime, in Mackenzie's blast-furnace*, and 

 afterwards the impure copper (containing iron) is re-smelted in the 

 reverberatory furnaces; and the waste slag from the cupolas 

 retains less than one half a per cent, of copper. Eight to ten hours 

 are usually required for each charge of 10 to 16 tons of mineral to 

 be smelted ; of this time two or three hours are given to poling in 

 order to render the copper tougher. 



After the appearance of the report of Dr. Houghton in 1841, 

 and for several years following, a wild mining fever seemed to have 

 been caused by the discoveries in the Lake Superior Region ; for 

 at the close of 1845 no less than 61 mining companies were 

 organized, of which 12 had commenced active operations, all 

 expecting to become suddenly wealthy. During 15 months 

 ending with November, 1845, no less than 592 mining locations 

 were granted by the Government to nearly as many persons. 

 Although eventually there were 111 mining companies formed, 

 whose locations spread over the whole length of Keweenaw Peu- 

 insula, a smaller number commenced work, as many of them 

 found they had " miuiug permits" without mineral. Of all 

 those that did begin operations and have since been organized, 

 only nine have paid dividends, and with one or two exceptions 

 these nine have paid handsomely, and" now three or four more, 

 after a long struggle, are promising to become lucrative. Some 

 of the failures have been the result of workiug lodes too poor to 

 pay, and moreover, in the early history of these regions, a great 

 deal had to be learned, as the percentage of copper is small and 

 in a different form from that of any other copper mining region, 

 and the necessarily great economy in working and handling the 

 rock was unknown. So great is the economy now that some mines 

 can win the rock, break and stamp it, concentrate and smelt the 

 copper for $3.50-$3.75 per ton for all the rock broken. Other 

 failures were due to gross mismanagement, and waste of money, 



