Page:Popular Science Monthly Volume 78.djvu/310

300 over sixty-two and one half million barrels were manufactured at about 80 cents per barrel as compared with 85 cents in 1908.

We are so accustomed to our wooden houses that we dread to have to give them up even when we know that in many other countries they are almost unknown. We are unmindful of Ruskin's dictum, "I would have our ordinary houses built to last," as well as, "built to be lovely, as rich and full of pleasantness as may be within and without." We are regardless of the thought that, instead of erecting a structure which can endure 50 to 100 years, it may be better to build for 500 to 1,000 years or more.

In other ways the chemist is conserving the forests; by guarding against one of the greatest dangers to our wooden edifices—fire—through fire-proofing processes, and against their bacterial foes, which cause decay, through wood preservatives. As to stopping the journey of our forests to the paper-mill, it appears not to be the time for that yet, but chemists are finding ways of replacing wood fiber in paper by others, notably those of grasses. Even if it should prove beyond the skill of the chemist and engineer to continue our present output of paper from the dwindling wood supply and should most of our Sunday papers be forced to curtail their issues, who will see in that any dire calamity?

Cement is frequently used to preserve not only wood, but in many places iron, and so conserves this material. Where more strength is required than concrete possesses, iron surrounded by cement has been found to last indefinitely. The process of reducing the crude iron from the ores has been steadily improved so that now, through such means as using the heat formerly wasted from the blast furnace to heat the air of the blast, to make steam and to dry the air before it is blown into the furnace, but a fraction of the coal is required that was formerly necessary. Similar savings have been made in other parts of the metallurgical field; for instance, in the recovery of gold and silver during the treatment of copper and lead ores, several million dollars worth being thus annually obtained, and this by the old methods would have been for the most part wasted.

The loss of by-products in the manufacture of coke has been referred to; but closer chemical supervision is rapidly reducing this. In 1905 over thirty-seven million tons of coal were coked in the United States, but less than 9 per cent, in ovens where these by-products were preserved. Two years later the amount coked in by-product ovens had increased about one half.

Foreign chemical engineers are setting us a praiseworthy example. In Gelsenkirchen, Germany, the coke ovens furnish illuminating gas to surrounding cities and villages at 23 cents per 1,000 cubic feet. Each ton of coal yields three to three and one half gallons of benzene, a valuable substitute for gasoline as a producer of heat and energy. From the