Paper, 'On the relative densities of hydrogen and oxygen. II' by Lord Rayleigh [John William Strutt] Strutt writes: 'In a preliminary notice upon this subject, I explained the procedure by which I found as the ratio of densities 15.884 [see PP/11/23]. The hydrogen was prepared from zinc and sulphuric, or from zinc and hydrochloric, acid, and was liberated upon a platinum plate, the generator being in fact a Smee cell, enclosed in a vessel capable of sustaining a vacuum, and set in action by closing the electric circuit at an external contact.' Annotations in pencil and ink. Includes two diagrams of experimental apparatus. Subject: Chemistry / Physics Received 5 February 1892 / 6 February 1892. Read 18 February 1892. A version of this paper was published in volume 50 of the Proceedings of the Royal Society as 'On the relative densities of hydrogen and oxygen. II'. 1892