The author commenced his paper by referring to the numerous researches on opium which had already appeared, and stated that notwithstanding their number and extent, our information on the properties and composition of its various bases and indifferent constituents was still extremely imperfect. He had therefore submitted some of them to a renewed examination, employing as the source from which they were obtained the mother liquor of the manufacturers of muriate of morphia. By treatment of this liquor in a manner detailed in full in the paper, he obtained from it a large quantity of narcotine, and a certain proportion of thebaine and narceine.