Letter from William Ramsay, to John William Strutt, Lord Rayleigh, regarding a paper 'The variation of molecular surface-energy with temperature' by William Ramsay and John Shields Outlines the precautions taken to minimise the risk of contamination in the apparatus and method. Provides reasoning for his conclusions. 'The proof of the pudding is in the eating, I think'. Comments on a paper by James Ballantyne Hannay that was read before the Society, whose formulae are 'utterly improbable'. Subject: Physics and Chemistry [Published in the Philosophical Transactions of the Royal Society, 1893] 3 June 1893