and fuel, a real conservation of resources. More recently as high grade ores suitable for the Bessemer process are becoming scarcer the metallurgist has added to his equipment the open-hearth furnace in which ores of a much inferior quality can be smelted.
The history of aluminum offers an even more striking illustration. For many years after it was isolated by Wöhler from its fused halogen compounds through the addition of metallic potassium it was somewhat of a chemical curiosity. Owing to the high cost of potassium the lowest price at which it could be sold was several dollars an ounce. It could not be bought in any large quantity. I distinctly remember the pride with which one of my earliest teachers of chemistry was wont to exhibit to his classes a piece of aluminum about as large as his finger, and with what delight he would tell of Wöhler's custom, in saying good-bye to his newly made doctors of philosophy, of bestowing upon those with whom he was particularly pleased a piece of the precious metal, this being such a fragment. That was not many years ago; yet in 1907 there were produced in this country 17,000,000 pounds which sold for about five million dollars—less than 30 cents a pound. And this was the answer of chemists and metallurgists to the demand for a light, permanent metal at moderate cost. What the future of aluminum may be we do not know. But being in abundance, the second of the solid elements and twice as large in amount as iron, its compounds can not possibly be exhausted.
Alizarin, which is one of the important vegetable dyes, was formerly obtained from madder, the root of a plant growing abundantly in the south of France and some other Mediterranean countries. The demand for it increased until thousands of acres were given over to the cultivation of the Rubia tinctorum. But in 1868 two chemists, Graebe and Liebermann, after long study, succeeded in preparing alizarin synthetically from anthraquinon, a coal-tar derivative. It drove from the market the natural alizarin. There was an outcry from those who had cultivated the crude material that their means of livelihood had been destroyed. But thenceforward the fertile fields which had been devoted to its growth were used to furnish foodstuffs to the country. A waste substance had been used and the old energy turned into better channels.
A similar history is that of indigo, one of the standard dyestuffs of our grandmothers—a product of the indigo plant. Adolf von Baeyer, chemist, of Munich, in 1870 overcame the difficulties of its synthetic formation and, from coal-tar again, by complicated methods prepared this substance, one of the most stable of our dyes. Other chemists have simplified the process until now it is formed in the factory, a rival of that from the field, and thus large tracts of land are released for other forms of agriculture.