174 Hot Blast in the Smelting of Lead. 



which it is agitated by cam C. The diggings from the crasher 

 being thrown into this sieve and the lever let into the cam, the 

 contents of the sieve immediately arrange themselves in strata 

 according to their relative gravities ; first, clean gangue on the 

 surface, next, ' middlings,' being spar with particles of ore attach- 

 ed, (these are thrown back to be recrushed,) next, lead ore, the 

 surface of which has more or less gangue adhering, the lower 

 strata nearly pure. The ore as smelted, contains from five to ten 

 per cent, of calc spar adhering and scattered through it. The 

 mineral which passes through the sieve is taken from the vat 

 and washed in a stream of water upon an inclined table, both so 

 graduated that the ore remains near the stream and the impuri- 

 ties may be carried off. 



The Rossie Lead Mines. — Of the bubbles of '36 and '37, per- 

 haps none was more unmercifully inflated than that of the Rossie 

 lead stock. It is imfortunate for the mining interest in that very in- 

 teresting and promising region, that this remarkable mine should 

 have become by a ten years' lease the property of a company, 

 and thus made at once the victim of speculation. In taking out 

 the ore for the first one hundred feet in depth, little expense was 

 necessary, and the product and profits were large. At the depth 

 now attained, say from one hundred and seventy five to two hun- 

 dred feet, permanent and adequate machinery and good engineer- 

 ing are required, having reference to working the mine for a long 

 series of years. The investments necessary for this can hardly 

 be looked for until the fee of the land and the rights to the mine 

 are owned by the same person or company. The amount of lead 

 smelted from these mines in 1837 and 1838, was 4,137,871 lbs. ; 

 in 1839, about 1,200,000 lbs. ; in 1840, about 400,000 lbs. 



The primitive rock, (hornblende gneiss,) in which this mine 

 lies, has but few fissures through which water is discharged, and 

 hence is easily kept free. It is already wrought one hundred 

 feet below Indian River, which flows some eighty rods distant. 

 Whatever may be the difficulties of the present unfortunate tenure 

 of this valuable mine, there is little doubt that it will eventually 

 be efficiently wrought and yield a uniform and adequate return. 

 The vein descends perpendicularly; the quantity of ore in a given 

 space holds about the same, and in all probability is inexhaustible. 



