This paper is supplementary to, and forms the sequel of, a series of papers which have been published in the “Quarterly Journal of the Chemical Society of London.”

In continuing the examination of the behaviour of the olefines towards compound halogens, certain compounds previously described have been submitted to a test of homogeneity, of which the following is the principle:—

“If a body be partly dissolved in a solvent, and if the dissolved part and the undissolved part, or the dissolved part and the whole, or the undissolved part and the whole, have the same composition, then the body is a simple one.”