Referee's report by William Augustus Tilden, on a paper 'The refractive index of gaseous fluorine' by Clive Cuthbertson and E B R Prideaux Sectional Committee: Physics and Chemistry Not recommended for publication in Philosophical Transactions. The earlier part of the paper to page 18 is unnecessarily lengthy, the details of experiments known to be unsuccessful should be omitted or reduced in bulk. The illustrations must be produced but require to be redrawn. The enquiry is one which involves great experimental difficulty which has been met by the authors with much patience and skill. The results can after all only be an approximation, and do not afford any fundamental principle. [Published in Philosophical Transactions A, 1906]. Endorsed on verso as received 21 June 1905. 21 June 1905