Referee's report by Hugh Longbourne Callendar, on a paper 'The refractive index of gaseous fluorine' by Clive Cuthbertson and E B R Prideaux Sectional Committee: Physics and Chemistry Receommended for publication in Philosophical Transactions, in full without modification. All the illustrations should be reproduced. In general the papers seems to be a valuable contribution to knowledge, and a most praiseworthy achievement in spite of great experimental difficulties. [Published in Philosophical Transactions A, 1906]. Endorsed on verso as received 17 June 1905. June 1905