Before giving the action of ethylene on the chlorides of iodine. I may shortly describe the method of preparing the latter, which I found to be the most advantageous:—
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A weighed quantity of perfectly dry iodine being introduced into bulb A of flask 1, perfectly dry chlorine gas is passed over it, A being at the same time heated over a water-bath to about 60° to 80° C. The ICl3, as it is formed, volatilises and condenses almost entirely in B, only a small portion escaping into flask 2. Chlorine is passed until no more iodine remains in bulb A. If the heating be omitted, only the outermost layers of iodine are converted into the trichloride, a kernel remaining unacted on. (Compare Christomanos, Berl. Ber. X. No. 5, p. 434.)