In this paper further evidence is put forward in support of a previous paper on the subject. Very soon after the reading of that paper, A. E. Mitchell read a paper before the Chemical Society on a closely related subject. Working quite independently, and employing other methods of investigation, Mitchell arrived at conclusions in close agreement with those detailed in the former paper. H.L.J. Bäckström has criticized Mitchell's paper, raising some objections 'against the experimental evidence produced aud the … way of interpreting it'. Where Bäckström objections touch on anything in Mitchell's paper which is incidentally akin to any of the work described in this or the earlier paper, they will be discussed herein.