Photochemical Reaction of Hydrogen and Chlorine

PROF. BAKER and I have talked over the matter dealt with in his letter to NATURE published in the issue of January 7, p. 27, namely, the influence of traces of water vapour on the above reaction. We agree that no further discussion of the point at issue would be useful unless combined with a simultaneous firsthand and detailed examination of the experimental method used. This is impossible, as the apparatus in question has been dismantled. We therefore, for the time being at all events, hold to our respective and divergent views on the subject.