A FURTHER contribution to the chemistry of their recently discovered iodonium bases, by Prof. Victor Meyer and Dr. Hartmann, will be found in the present issue of the Berichte. In their two former communications, an account of which will found in NATURE, vol. xlix. pp. 442 and 467, in addition to the free parent base (C6H5)2I.OH, descriptions were given of the iodide (C6H5)2I.I, the chloride (C6H5)2I.Cl, the bromide (C6H5)2 I.Br, and the pyrochromate [(C6H5)2I]2 Cr2O7. Several new salts are now described, most of which crystallise well, and several are endowed with properties of a particularly interesting character. The similarity to the salts of thallium becomes even more apparent as the reactions of the derivatives are elaborated. The hydroxide has already been shown to be an easily soluble and an alkaline substance; the carbonate is likewise soluble in water and exhibits an alkaline reaction, and the halogen compounds are similar in colour, solubility, and other physical properties to the corresponding thallium salts.