Modem chemistry is essentially experimental; the unprecedented magnitude to which British manufactures have risen is chiefly owing to experiments conducted with consummate skill and dexterity. In these investigations, accidental circumstances have sometimes occurred which led to other researches quite different from that originally in view, which have had unexpected and invaluable results. Although the simple elements are few, they are capable of an infinite variety of combinations, so that by analysis and new combinations, the most useful and valuable materials are now obtained from obnoxious or useless substances, formerly thrown away. The instances are numerous; but sawdust may be mentioned as one of the most remarkable. It was not even fit for fuel, but now oxalic acid, a bleaching principle most extensively used in the various processes of calico printing, is procured from it; the quantity required may be imagined, since the cotton cloth annually printed in Great Britain previous to the American war, would surround the earth’s equator nineteen times. Oxalic acid, which is a vegetable substance, found combined with potash in wood sorrel or Oxalis acetosella, used to be made from sugar or starch, by the action of nitric acid. Now starch, sugar, and woody fibre or fibrine, all contain twelve parts of carbon and different portions of oxygen and hydrogen, always in the proportions that form water; hence the name of carbohydrates. Their composition is so similar that the one may be changed into the other by the addition or subtraction of one or two atoms of water under its atomic form; thus when fruits ripen, the starch they contain is changed into sugar by the addition of one atom of water under its dry form. Now sawdust is woody fibre, and might be changed by nitric acid into oxalic acid like the others. But a less expensive method is actually employed.