This paper contains some details of a continued investigation, of which the first results were communicated to the Chemical Society of London last year. It was then shown that new bases are produced by the action of iodide of methyl and of ethyl upon morphia and codeine, which are closely analogous with the ammonium bases of Hofmann, so that these alkaloids should rank among nitryle bases. The fact was also pointed out, that although one of the new salts produced had precisely the centesimal composition of the corresponding compound of codeine, the base of the artificial product was widely different from this alkaloid; and the conclusion was drawn that the primary molecules of these natural formations are of so peculiar a constitution, that chemists are not yet in the possession of means of imitating the process of their construction; for even the attempt to convert morphia into codeine fails, though the addition of the requisite amount of carbon and hydrogen to the former is readily effected.