Page:Popular Science Monthly Volume 74.djvu/281

Rh it amounts to over six hundred million tons. Such a mass will measure up nearly twenty-six billion cubic feet. Put this into the form of a pyramid, with a base ten thousand feet square (about twenty-three hundred acres) and its height would be nearly eight hundred feet. Or, cut down the base to dimensions of a five thousand foot square (say sixty acres) and the structure would be nearly two thirds of a mile high. It may not be so difficult then to agree with the iron producers who claim that another half century of such strenuous civilization as the last one will serve to exhaust all the known great iron deposits of the world. Who of the generation that saw the Civil War would have imagined such an expansion of an industry that was then but lightly regarded even by economists? It is indeed high time for the chemists and metallurgists of the day to redouble their efforts to solve the problem of the cheap production of aluminum, for in that direction only does there seem to be an escape from the dilemma of a world unable to procure the common metal it needs, if its civilization is to continue.

In the case of lead we come down to more ordinary figures, yet none the less surprising when the services the metal gives us, by reason of its peculiar qualities, are considered. Without lead, no paint, no shot or bullets, no flexible piping. These are the three principal uses to which it is put in these days, and more than half of the annual crop of the mines becomes paint, and is employed to protect and improve the appearance of the structures that man raises to live, and to transact his business in. In 1885 the world turned out 391,542 tons of the metal. Lead is a dense and heavy substance, and it only requires a cube measuring a short seventeen inches along its edges to weigh a ton. Even so, the production of the year 1885 would make a mass covering a quarter of an acre of ground, and standing nearly one hundred and ten feet high. But when the year 1906 closed, and its doings were figured out by the statisticians, it was found that the lead mines of the world had turned out in that twelve months nearly three times as much as they had in 1885. To be accurate, the crop amounted to 1,061,533 tons. This mass of metal would make a pyramid with a base one hundred and fifty feet square, and rising nine hundred feet into the air. An increase of 300 per cent, in twenty years indicates an enormous growth in the demand for paint and putty, to say nothing of the consumption in the way of ammunition and piping.

Mercury is the one degenerate in the family of the metals. Between 1850 and 1860 it was tremendously in demand by the miners