IN your issue of the 23rd ult. (p. 284) you insert a paragraph describing experiments by M. Chabrie on compounds of selenium. While fully acknowledging the value of his work on the phenyl derivatives of selenium, I think it right to state that much of M. Chabrie's investigation has been anticipated by Mr. F. P. Evans and myself as long ago as 1884; and that several of his assertions are incomplete and incorrect. The tetrachloride, SeCl4, as we then showed, exists in vapour as such between 180° and 200°; with rise of temperature it dissociates, but even at 360°, dissociation is incomplete. In our paper (Trans. Chem. Soc., 45, 62) the progress of the dissociation is followed.