WE are able to confirm the observations of D. P. Mellor and T. Iredale 1 on the photo-reaction between iodine monochloride and hydrogen, as against the photo inactivity of the mixture reported by Rollefson and Lindquist.2 A rapid photo-reaction between these substances when not specially purified had been observed by us before the appearance of Rollefson and Lindquist's paper ; the reaction, however, is much influenced by traces of impurities, for when special pains are taken to avoid contamination by organic materials, stopcock grease and the like, the rate of reaction under the influence of light is much decreased. There remains, however, an easily measurable reaction under the influence of the light of a mercury arc. The main products are hydrogen chloride (HC1) and iodine (I2); no appreciable amount of hydrogen iodide has been found. The photo-reaction between iodine chloride and methane has also been established in this laboratory ; the rate here is great compared with that of the hydrogen reaction. Both reactions are being investigated in detail.
NATURE, 127, p. 93, Jan, 17, 1931.
Jour. Amer. Chem. Soc., 52, 2793; 1930.