In a paper on the crystalline constituents of opium, read before the Royal Society of Edinburgh, I described a process for separating thebaine from papaverine and narcotine, withwhich it occurs mixed in the opium liquor I examined. This process consisted in converting the mixed bases into acetates, and adding to the solution an excess of subacetate of lead, by which the feebler bases are precipitated, and the stronger thebaine left in solution.

As it is familiarly known that in those plants in which alkaloids are found, they rarely occur singly, but are generally associated in groups of two or more, often very closely allied in their properties, and consequently require for their separation, processes of considerable complexity, I have been induced to make a few experiments, with the view of ascertaining whether the method I had applied with success to the opium bases could be used for other substances.