Letter from Eric Keightley Rideal, on a paper 'Diffusion and chemical reaction velocity in cylindrical systems of physiological interest (with an appendix of spherical systems)' by Francis John Worsley Roughton, to D C Martin Paper reference code: A23 Rideal writes: 'Dear Martin, Many thanks for your letter of the 14th March. I certainly have no objection to Rougton knowing my name, but, unfortunately, I have come down with a duodenal ulcer, and I think that the question of discussion of this paper is off for sometime to come. I do not know whether I can contribute much to the discussion; I only thought that Roughton had used a sledge hammer to deal with a subject that it still rather tentative. With kind regards, Yours sincerely, Eric K Rideal'. Written at University of London King's College, Department of Physical Chemistry, Strand [England]. [Published in Proceedings B, 1952]. Endorsed on recto as received 20 March 1952. 19 March 1952