There are large areas of copper lands which are now classed as "available" with copper at about its present price of thirteen cents a pound. If the world production should grow so great as to cause a decided drop in the price, much that is now considered available could not be mined at a profit, and the copper supply from this country would be greatly reduced. If, on the other hand, copper should rise to fifteen or twenty cents or higher, the amount of available copper land would be vastly increased. The report on the Conservation of Mineral Resources says in effect: "The copper resources of the United States are believed to be large enough to allow for a number of years for a demand increasing at the rate of 30,000,000 pounds a year. Should this demand continue for a long period the scarcity would be felt and result in a rising price, which would open up a market for these low-grade ores and also cause the use of other metals, like aluminum, to take the place of copper whenever possible." There is no great waste in the mining of copper, but in the extraction of copper from the ore the waste is often as much as thirty per cent., and it is not easy to avoid this on account of the chemical changes that take place. LEAD The United States produces about one-third of the lead in the world. The remainder comes from Spain, where the production remains about the same from year to year; from Germany, where in spite of higher prices production is growing less; and from Australia and Mexico, in both of which the supply is rapidly decreasing. These facts show that the lead resources of the United States will be drawn on heavily in the future. The production of the United States increased from about 70,000 tons in 1880 to 365,000 tons seventeen years later, and if continued the yearly production 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.