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IN a previous paper (Dawson and Leslie, Trans., 1909, 95, 1860) it has been shown that iodine reacts readily with acetone at the ordinary temperature, and that when aqueous solutions containing acetone and iodine are acidified by addition of a mineral acid, the reaction proceeds at a rate which is suitable for accurate quantitative measurements. These observations showed that when the acetone is present in considerable excess, the rate of disappearance of the iodine is practically constant from the commencement until near the end of the reaction, the velocity being proportional to the concentration of the acetone and of the added mineral acid.To account for these facts, the view was adopted that the reaction between acetone and iodine involves two stages. I n the first of these, the acetone is converted from the ketone into the enolic form, and this is then acted on by the iodine at a relatively very rapid rate with the formation of iodoacetone. In consequence of the very great difference in the velocities of the consecutive reactions, the rate of disappearance of the iodine is determined solely by the rate at which the acetone is transformed into the enolic form (compare Lapworth, Trans., 1904, 85, 30).I f this is the correct interpretation of the facts, it is evident that the investigation of the velocity of reaction of iodine with other ketones should lead t o information respecting the rates at which the various ketones undergo tautomeric change. With this object in view, experiments were made to compare the rates of disappearance of iodine in dilute acidified solutions of dimethyl, methyl ethyl, methyl propyl, methyl butyl, methyl hexyl, phenyl methyl, diethyl, and phenyl ethyl ketones. On account of the small solubility of certain of these ketones in water, the comparative measurements could not be made in aqueous solution, and instead of this, an aqueous alcoholic solution containing forty volumes per cent. of ethyl alcohol was employed. I n this connexion experiments were made to ascertain the influence of the medium on t.he reaction between acetone and iodine in alcohol-water mixtures ranging from pure water to pure alcohol. The results of this investigation will be communicated in a further paper. For the present it is sufficient t o state that the reaction between the two substances is of the same character in alcoholic as in aqueous solution, and that, for a given concentration of acetone and acid, the rate of disappearance of iodine is practically the same in alcohol-water mixtures as it is

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The photoconductivity within a wavelength range of 450-1100 nm was determined for a sample of epitaxial delafossite CuFeO 2 film grown by pulsed laser deposition. The film thickness was estimated to be 75 nm. The resistance of the films was determined with four-contact van der Pauw's method and using monochromatic illumination of the film. The most significant change in resistance resulted in three rapid lineal conductivity increases at photon energies of ~ 1.5 eV (gap-1), ~ 2.1 eV (gap-2) and ~ 2.5 eV (gap-3). The conductivity properties are well correlated with prior optical absorption results obtained in the NIR-VIS region using transmittance spectroscopy.