Letter from Nevill Francis Mott, on a paper 'the interaction between the radiation field and ionic crystals' by Kun Huang with 'Additional note: Energy density of monochromatic radiation in a dispersive medium' by H Pelzer, to D C Martin, Assistant Secretary of the Royal Society Paper reference code: A239 Mott remarks: 'Dear Martin, I have made a few alterations to the English of Huang's paper and now recommend that it goes forward for publication. Yours sincerely, N F Mott'. Written at University of Bristol, H H Wills Physical Laboratory, Royal Fort, Bristol [England]. [Published in Proceedings A, 1951]. Endorsed on recto as received 11 April 1951. 10 April 1951