130| .290| 26 | .52
==========================================================================

In these figures the writer has not followed strict averages, but
has taken the general outlook combined with the previous records.
The likelihood of higher prices for lead is more encouraging than
for any other metal, as no new deposits of importance have come
forward for years, and the old mines are reaching considerable
depths. Nor does the frenzied prospecting of the world's surface
during the past ten years appear to forecast any very disturbing
developments. The zinc future is not so bright, for metallurgy
has done wonders in providing methods of saving the zinc formerly
discarded from lead ores, and enormous supplies will come forward
when required. The tin outlook is encouraging, for the supply from
a mining point of view seems unlikely to more than keep pace with
the world's needs. In copper the demand is growing prodigiously,
but the supplies of copper ores and the number of copper mines
that are ready to produce whenever normal prices recur was never
so great as to-day. One very hopeful fact can be deduced for the
comfort of the base metal mining industry as a whole. If the growth
of demand continues through the next thirty years in the ratio of
the past three decades, the annual demand for copper will be over
3,000,000 tons, of lead over 1,800,000 tons, of spelter 2,800,000
tons, of tin 250,000 tons. Where such stupendous amounts of these
metals are to come from at the present range of prices, and even
with reduced costs of production, is far beyond any apparent source
of supply. The outlook for silver prices is in the long run not
bright. As the major portion of the silver produced is a bye product
from base metals, any increase in the latter will increase the
silver production despite very much lower prices for the precious
metal. In the meantime the gradual conversion of all nations to
the gold standard seems a matter of certainty. Further, silver
may yet be abandoned as a subsidiary coinage inasmuch as it has
now but a token value in gold standard countries if denuded of
sentiment.

COST OF PRODUCTION.

It is hardly necessary to argue the relative importance of the
determination of the cost of production and the determination of
the recoverable contents of the ore. Obviously, the aim of mine
valuation is to know the profits to be won, and the profit is the
value of the metal won, less the cost of produ