Copy letter, from Sir John Herschel to James P. Murchison, dated at Collingwood Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Thanks James P. Murchison for a copy of the Correspondence of the Late J. Watt. In commenting on it, John Frederick William Herschel discusses at some length the doctrine of phlogiston as it relates to the discovery of the composition of water. 23 March 1847