In April 1846, I communicated to the Royal Society a paper on a new organic base, to which I gave the name of Picoline, and which occurs in coal-tar, associated with the Pyrrol, Kyanol, and Leukol of Runge. In that paper I pointed out that the properties of picoline resembled, in many respects, those of a base which Unverdorben had previously extracted from Dippel's animal oil, and described under the name of Odorine; and more especially mentioned their solubility in water, and property of forming crystallisable salts with chloride of gold, as characters in which these substances approximated very closely to one another. And further, I detailed a few experiments on the odorine of Unverdorben extracted from Dippel's oil, with the view of ascertaining whether or not they were actually identical, but on too small a scale to admit of a definite solution of the question.