In this year the great fever drug quinine was first clearly separated and identified by Drs. Pelletier and Caventou, who were spurred on to their labors by the previous experiments with the drug by Drs. Gomez and Lambert. In its crude form the bark of the chinchona tree had been used for its medical properties since times immemorial. [Sidenote: Homeopathy] It was about this time that the German physician Hahnemann's theory of homeopathy caused general discussion among medical practitioners and laymen. Hahnemann's first thesis was that many diseases could most quickly be eradicated by similar effects--fever with fever, poison with anti-poison. This theory of "like with like"--the Greek homoia homoiois--was accordingly named by him homeopathy. It was most fully expressed in his "Dogma of Rational Healing" and in the later treatise "Chronic Ailments and their Homeopathic Cure." These books created such a widespread sensation that they were at once translated into several languages and ran through a great number of editions. As a matter of course, Hahnemann's peculiar theories were violently combated by his fellow practitioners. [Sidenote: Hydropathy] Almost at the same time with the rise of the new science of homeopathy came Vincenz Priessnitz's innovation of hydropathy or water cure. He established his first sanitarium at Grafenberg, his birthplace, and in the face of vehement medical opposition soon won government recognition for his sanitarium. Similar water-cure establishments were erected by many imitators and followers in Germany and elsewhere. [Sidenote: Convention of Troppau] [Sidenote: Intervention in Naples]