Letter from Ronald George Wreyford Norrish, on a paper 'Energy per-ion-pair for electrons in gases and gas mixtures' by J M Valentine Paper reference code: A161 Norrish returns J M Valentine's paper, he is unsure why the paper was sent to him as it concerns 'pure physics'. However he has answered the questions to the best of his ability. Written at University of Cambridge, Department of Physical Chemistry, Free School Lane, Cambridge [England]. [Published in Proceedings A, 1952]. Endorsed on recto as received 13 August 1951. 11 August 1951