known as that of the latter. Years after the effects produced by the inhalation of chloroform were discovered, Liebreich reasoned thus: If chloral breaks up in alkaline liquids into chloroform and formic acid, why should it not break up in the same way when introduced into the animal system? The conditions in the body are favorable for such a decomposition—the blood is an alkaline liquid and the chloral will dissolve in it. By means of this reasoning the discovery was made, and there is no cause to doubt that the beneficial effects experienced from chloral are due to the fact that the alkaline blood decomposes it, forming chloroform and formic acid, the chloroform being thus introduced into the system in a manner differing from that involved in the inhalation process.
As regards salicylic acid, its discovery was the result of a long series of purely scientific investigations. For years Kolbe had been trying to produce artificially in his laboratory some of the substances which are found in nature. He strove faithfully and conscientiously to accomplish his purpose, and at last he discovered a method which enabled him to make oxalic acid; and then, after the method was given, the production of other similar acids was simply a question of the application of the new method. Salicylic acid was among the products thus formed. The acid had been known for a long time, but, as it could be obtained only from the expensive oil of wintergreen, it belonged to the rare substances. Kolbe's method of preparation, however, furnished the substance in large quantities and at a low price.
The discovery of the valuable antiseptic properties of the acid was a pure scientific discovery, and was due to purely chemical reasoning. It was known that salicylic acid when heated breaks up directly into carbolic acid and what is commonly called carbonic acid. It occurred to Kolbe that possibly this property might be taken advantage of to furnish a substitute for the objectionable carbolic acid. The results of his experiments are well known: they were more satisfactory than he had hoped for. He found that salicylic acid is an excellent antiseptic. Though he has shown that, contrary to his expectation, the antiseptic action possessed by the acid is not due to its breaking up into carbonic and carbolic acid, still the action must be due to a similarity between the chemical structures of the two acids; and this similarity could not have been detected without the aid of some of the most refined methods of scientific chemistry. It is safe to say that blind experiment, unguided by definite chemical principles, could not have led to this discovery.
Thus I have at least illustrated the truth of the remark I made a few minutes since, to the effect that the discoveries of substances valuable in medicine are made by those engaged in the pursuit of pure science. I am aware that the two examples thus referred to will not suffice to furnish a perfect proof of the proposition; but, if time per-
