Amount of substance used .66640 gr. ” ” bromine found .36953 ” Bromine. 55.45 per cent. Second determination of bromine: Amount of substance used .56035 gr. ” ” bromine found .31085 ” Bromine. 55.47 per cent. The percentage of cadmium and bromine found agrees very closely with that of a compound of the formula Cd₄Br₇. The relation of cadmium to bromine in this would be: Cadmium. Bromine. 44.44 per cent. 55.56 per cent. When this compound was heated for a long time with an excess of the metal its composition was not appreciably changed. The compound Cd₄Br₇ is a strong reducing agent: giving with nitric acid oxides of nitrogen, with dilute hydrochloric, sulphuric or acetic acid, free hydrogen, and with mercuric chloride, mercurous chloride or metallic mercury. The action of water on the bromide by means of which cadmous hydroxide was formed, was not studied as carefully as with the chloride but appeared to be essentially the same. The Preparation of Cd₁₂I₂₃. Cadmic iodide was prepared in the same manner as the bromide. It was dried in a stream of hydriodic acid gas at as low temperature as possible to lessen the decomposition of the hydriodic acid. When the anhydrous iodide was heated with an excess of metal in an atmosphere of nitrogen the red color of the iodide became intensified. Heating was continued until there was evidence of dissociation, which, under the same conditions, was less marked than with the chloride and much less than with the bromide. Owing to the high specific gravity of the iodine compound some difficulty was experienced in obtaining a preparation free from metal. This difficulty was finally overcome by keeping the material just above its melting temperature for a long time and constantly jarring the flask. During the process of cooling a decidedly greenish tint was observed which disappeared as the process was continued. When cold the substance resembled the chloride and bromide. Two determinations of cadmium were made in the first preparation. First determination: Amount of substance used .55540 gr. ” ” cadmium found .17456 ” Cadmium. 31.43 per cent. Second determination: Amount of substance used .47535 gr. ” ” cadmium found .14980 ” Cadmium. 31.51 per cent. As these results did not correspond to the composition represented by the formula Cd₄I₇, which our experience with the chloride and bromide had led us to expect, we reheated the material for several hours with an excess of the metal. Two analyses of the product gave: Cadmium. Iodine. 31.44 per cent. 68.65 per cent. 31.39 68.68 showing that the iodide had taken up during the first heating all the metal which it could retain. The analytical results suggest the formula Cd₁₂I₂₃, in which the calculated percentages are: