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 Sectional committee: Mathematics Paper reference code: A239 Mott disagrees with the referees comments on Huang's paper, and remarks 'he brings a very interesting clarification into the subject'. Recommends the paper for publication, but suggests it should be overlooked by an English physicist as the language 'is awkward in places'. Written at University of Bristol, H H Wills Physical Laboratory, Royal Fort, Bristol [England]. [Published in Proceedings A, 1951]. Endorsed on recto as received 9 March 1951. 8 March 1951