Referee's report by Hugh Longbourne Callendar, on a paper 'Calcium as an absorbent of gases for the production of high vacua and spectroscopic research' by Frederick Soddy Sectional Committee: Physics and Chemistry Not recommended for publication in the 'Philosophical Transactions of the Royal Society'. Would prefer the paper went to the Proceedings. Considers paper long and repetitive. Illustrations already published in the Patent Specifications. Refers to work of Maquenne, Rondt [?], and Hugh Longbourne Callendar and N N Evans ['The Behaviour of Argon in X-Ray Tubes', Nature, Vol.56, No.1461, p.624 doi:10.1038/056624a0], Hugh Longbourne Callendar [Phil. Trans. 1896], and comments by Arthur Schuster. [Published in the 'Proceedings of the Royal Society of London'] Endorsed on verso as received 28 September 1906. [September 1906]