Having familiarized myself, in connection with the letter by A. N. Murin, with the previously unknown works of A. E. Poleshchitskii and A. N. Murin, I must fully agree with the content of the indicated letter. A. E. Poleshchitskii, as early as 1944 (DAN 45, No. 6, 238), definitely pointed out that the exchange of bromine or chlorine ions in the systems AgBr or AgCl (in the precipitate)—Br\(^{-}\) or Cl\(^{-}\) (in solution) can be explained only by recrystallization of the precipitate, and not by self-diffusion within the volume of the precipitate itself. This point of view was experimentally confirmed by A. N. Murin (DAN 74, No. 1, 65 (1950)) earlier than by Cimen.

A. Kheĭfman

*) The results of these experiments, published in DAN 74, No. 1, 65 (1950), evidently also remained outside the reviewer’s field of view.