to the valuable substances included in the materia medica, he would stop when he had established the fact that this substance—just born—has such and such medicinal properties. He might discover a few substances in this way, but, unless work of another kind were going on simultaneously, which would furnish him with new methods, with new guiding principles, the possibilities of new discoveries would soon be exhausted. It is absolutely necessary, then, that purely scientific and abstruse problems should engage the attention of chemists, if the science is to grow; and it is further necessary that the science should grow, in order that new methods for the discovery of new substances may be introduced. It is the chemist proper who furnishes the new method; it may be that the chemist proper also discovers the valuable remedy, though one who simply applies the truths of chemistry may make the discovery.
As a matter of fact, it can be shown that it is to the purely scientific chemist, working with the main object of building up the science, that we owe the discovery of most valuable remedies, at least of those which are strictly speaking chemical compounds. I select for this purpose two substances which have but comparatively recently found their places in the materia medica—viz., chloral and salicylic acid. How and by whom were these substances discovered and introduced into medicine?
Nearly fifty years ago the great master Liebig undertook the study of the decomposition which alcohol undergoes when treated with chlorine. Other observers had noticed the fact that alcohol is decomposed by chlorine and that an oily product is formed, but the nature and composition of this product were unknown. Liebig undertook then simply to study this decomposition for the sake of throwing light upon the general subject, the action of chlorine upon alcohols. His investigations soon led him to the discovery of a new substance which possessed peculiar chemical properties, distinguishing it from all other compounds then known. This was chloral–the name being derived from the first syllable of chlorine and the first syllable of alcohol. Of the action of this substance upon the system, Liebig did not dream; but the study of its properties which he made at that time furnished the material that enabled Liebreich, forty years later, to dream in a very rational manner concerning its action upon the system. Liebreich's discovery of the value of chloral could not have been made by one unversed in chemistry. His experiments were undertaken in the true scientific spirit, and were suggested by a purely chemical method of consideration.
Among other facts concerning chloral which had been established by Liebig was this that in the presence of alkalies it breaks up into formic acid and the substance which we now know by the name chloroform. Chloroform was thus discovered by Liebig at the same time with chloral, but the action of the former upon the system was as little
