Whilst these deposits were being mined and operated farmers were in the habit of making their own concentrate in crude sluice boxes. The product thus obtained averaged about 35 per cent. monazite. The concentrates were then sold to a refinery, where it was best treated by electromagnetic separators, such as the Wetherill machine. The final product obtained from these machines was ready for chemical treatment for the extraction of the thorium. Practically the same treatment is given to the monazite from Brazil and India. As the concentrate obtained is of much higher grade, the additional charges for freight and duty, which are not borne by the Carolinas product, are more than offset. Undoubtedly, unless a very high tariff is placed on the monazite from Brazil and India, our future supplies will come from these two sources, at least for some time. It is very doubtful whether with a high tariff the Carolina deposits could furnish the monazite required in this country, even for a few years, and under the most favorable conditions it would take some time, possibly six months to a year, to revive the industry. The Allies and practically the whole world are dependent upon the United States for the manufactured products, thorium nitrate and gas mantles. Whether this monoply will continue is doubtful, as there is a movement in England to encourage both the thorium nitrate and the gas-mantle industry. CHAPTER XIV COPPER BY F. W. PAINE INTRODUCTION One country stands pre-eminent as the world’s great producer of copper, and that is the United States, whose production was 60 per cent. of the total world output in 1917. Iron, coal, oil and copper are fundamental raw materials of which the United States produces more than any other country, but only in copper and in oil is the output greater than that of all other countries together. In copper this has been true since the early nineties. American copper, English gold, Russian platinum and Chilean nitrate are common phrases in world markets; as common as the commodities themselves. No other country produces or has for many years ever produced one-sixth as much copper as the United States. While the world output of copper has been increasing, at the average rate of 5 per cent. annually for 10 years up to 1914 and three times as rapidly since then, the relative importance of the United States has not declined. On the contrary it has increased at a greater rate than the total world output. Certain individual countries, it is true, have since 1914 increased their output faster than the United States, but there is no indication that the United States will lose its present dominating leadership.