Letter from John Edward Lennard-Jones, to Alfed Charles Glyn Egerton, regarding a paper 'The replusive forces between isotopic molecules' by Ronald Percy Bell Sectional Committee: Physics Does not know where the delay could have occurred. In view of the long delay since communication, it should be published. Does not agree with the comments of Cyril Norman Hinshelwood, but does not think there is point in arguing the matter further. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on recto as received 3 January 1940. 2 January 1940