No. 50.] 
253 
There is now a back* with an average depth of perhaps 150 feet on 
the slope of the vein, ready for removal by the miner, and ready drain- 
ed, so that if large bodies of ore exist there, they can now be removed 
without additional expense, except that merely of mining, since all the 
necessary preliminary expenses have already been incurred. 
The advantages of these mines are, 
1st. Contiguity to water transportation and nearness of market. 
2d. Great depth to which they may be drained without machinery. 
3d. Abundance and cheapness of fuel for smelting. 
The disadvantages are, 
1st. Uncertainty of the quantity of ore. 
2d. The more or less intimate mixture of the galena and blende. 
3d. The sihcious nature of the gangue. 
The explorations in progress will demonstrate the probability or im- 
probability of the mines being prospectively productive. 
The mixture of the galena and blende offers a practical difficulty in 
the smelting operation, and various methods have been tried to effect a 
separation, so as to be enabled to smelt the ore and obtain the lead ; 
but they have not proved successful up to the present season. At the 
time of my visit, they were erecting shaking washing tables, which, (if 
the ore be first crushed or stamped, and then separated into uniform 
sizes by screens of different degrees of fineness,) it is presumed will be 
successful. 
The process for separating the blende or zinc ore, will also separate 
the greatest portion of the silicious matter, so that if the shaking wash- 
ing tables effect the separation, the future value of the mines will de- 
pend only on the quantity of ore. 
There is a strong probability that there are valuable deposits of lead 
ore in the Shawangunk mountain, since so much lead ore has been ta- 
ken from this and other mines, and from its having been found in so 
many places. 
The zinc ore in the Shawangunk mine, as far as it has been worked, 
is believed to have exceeded the lead ore in quantity. At the time of 
my visit, they were taking out large quantities of both these ores. 
* The " &ac/c," in mining phraseology, means the mass of a vein that has notl)een 
removed, and lying above the galleries that have been opened. 
