Referee's report by Arnold William Reinold, on a paper 'The velocity of the ions produced in gases by rontgen rays' by John Zeleny Sectional committee: Physics and Chemistry Recommended for publication in Philosophical Transactions in full without modification and including all the accompanying illustrations. The paper is an important one and the experiments appear to have been carried out with due consideration of possible sources of error. By an ingenious method the separate velocities of the different ions are measured. Previous observers had determined the ratio and the sum of the velocities in some cases. [Published in Philosophical Transactions A, 1900]. Endorsed on verso as received 3 March 1900. 2 March 1900