284 GEOLOGICAL SURVEY 
a series of bowls, one revolving within the other, and placed so that the ore could pass from one 
pair of bowls to the next, until the grinding and amalgamation was completed. 
Fig. 47. 
= 
) 
These are all the machines that are in use in the gold regions of the Southern States; and _per- 
haps if they were well constructed and properly managed, they would leave little to be desired; but 
it is quite certain that a considerable portion of the gold is lost. This is rendered evident by the dif- 
erence between all the assays made and the actual amount collected, as well as by the gold almost 
invariably found below the mill, and which must have escaped. 
This has led some to direct their attention to the probability of discovering some process of smelt- 
ing, which might obviate this difficulty. Smelting is practiced in Europe, but only with rich auri- 
ferous sulphurets. Those are roasted and melted into mattes, which are again roasted, and fused 
with lead; the gold is taken up by the lead, from which it is separated by cupellation. But even 
this is considered uncertain, and but little practiced. Poor iron ores, containing gold, have been 
smelted in the ordinary way, and the iron got rid of by conversion into sulphate of iron, which has 
a commercial value, and the gold remains. 
Now there is no mine in the State where a pyritous ore, sufficiently rich or abundant, occurs to 
render this process at all available. There is, indeed, an iron ore in York District, which contains 
gold, where an experiment may be tried. But the proposition to smelt the ordinary ores of the 
State, consisting for the most part of quartz and talcose slates, and containing about fifty cents in 
the bushel, of the precious metal, need not occupy much space in the discussion. 
It is not very easy to form a correct estimate of the productive value of the gold mines of the 
State, for assays of gold ores, in the small way, are not at all reliable, as every one knows, who 
has had any experience in the matter—and the specimens generally exhibited, give as fair a view 
