judge by the way of its production, is not likely to contain any ingredients found in living plants. The preparation of salicylic acid from the products of coal-tar was discovered by Kolbe about twenty years ago, inducing a more thorough study of the properties of this acid, from which it was found to be one of the most valuable remedies for rheumatic complaints and for gout. Thus one discovery often becomes the source of a whole series of new ones, and may prove a blessing to mankind in the most unexpected and various ways.
Few people know what xanthin is. The name, indeed, represents a body of neither commercial nor industrial significance. Scarcely anybody else but chemists and physicians knows that it is a substance which, in a small amount, is found in muscles, in the liver, brain, and certain other organs of the animal body. But little, therefore, does he who enjoys a cup of cocoa, coffee, or tea, fancy that the beneficent, animating effect of these beverages is due to the methyl compounds of xanthin, contained as theobromine in cocoa-beans and as caffeine, in coffee-beans and in the leaves of tea and several other plants. Both theobromine and caffeine can readily be prepared from xanthin, the products having exactly the same physiological effect as the natural compounds.
The line of products of organic life which have been built up artificially from their constituents includes representatives of many groups of compounds, although they are not equally numerous in all of them. A large number of vegetable acids may be synthetically prepared. The volatile oils of bitter almonds and mustard, as well as the coloring matters indigo and alizarin, besides being prepared from plants, are obtained from other sources by chemical processes; but, since their original production depends on fermentative actions, to which the material is subjected, they can not justly be classed among natural products. In some groups of natural organic compounds our efforts to obtain them by synthesis have hitherto almost utterly failed. Our knowledge of alkaloids, many of which, by their great physiological effects, are of prominent therapeutic importance, has advanced so far as to permit us to convert some of them into others—for instance, to transform morphine into codeine; but, with the exception of conine, which Ladenburg claims to have synthetically obtained, and conhydrine, prepared by Hoffmann, both of which are contained in hemlock (Conium maculatum), no success of consequence has been registered. Nevertheless, as the knowledge of their chemical structure has been cleared up to a very considerable degree, we may expect that, by continued researches, ways for their artificial manufacture will be found out.
Many chemical discoveries were made by accident; compounds of valuable properties were found by researches under-
