Tion by 1920 will amount to 580,000 tons, or more than a billion pounds. The principal lead-producing states are Missouri, Idaho, Utah, and Colorado. In Missouri it is probable that the present rate of increase could be kept up for at least fifty years. The other states could keep up the present production for many years but could not greatly increase it without exhausting the supply. As with most mineral resources in the United States, it is only the richest ores that are now drawn upon (except where lead is a by-product extracted with some other ore). If prices would advance, so as to make the low-grade ores profitable, the amount of our resources would be greatly increased. There is little waste in the mining or smelting of lead ores, and the slag, the waste, is always ready to be used again. In the refining and concentrating of lead the loss often amounts to as much as fifteen per cent. or twenty per cent. The best way to prevent final loss is to store all refuse until such time as the reworking becomes profitable. Improvement in methods has been great in the last fifteen years but more economical methods everywhere will be one of the necessities of the future. We can see that the lead resources of the United States are not large and that when our own supply is exhausted we can not turn to the rest of the world. The waste in mining is not large, and most of it can not be avoided at present prices; so that for the conservation, which we see is so important, we must turn to the uses of lead. The most necessary of these is for lead pi
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