Discovery of the Composition of Water. 45 



at the Royal Society, and farther, that it was in the hand- 

 writing of Mr Cavendish's friend. Sir Charles Blagdon. That 

 letter to M. de Luc it was, no doubt, which gave rise to the 

 explanation contained in the interpolated statement; and the 

 circumstance that it was not in Mr Cavendish's own hand- 

 writing in the MS., it seems most natural to infer vv'ould not 

 denote that anything unfair was practised. Had Mr Caven- 

 dish not been confident that he was acting correctly, had he 

 been performing the part of a plagiarist, he would, it maybe 

 presumed have acted with tlie caution of a plagiarist at the 

 time. The correctness of the statement, it should be remem- 

 bered, was not impugned, as, if incorrect, it surely ought to 

 have been. 



I have spoken of Mr Watt's conclusion of the compound 

 nature of water as an hypothesis, or as an inference from 

 an experiment requiring to be confirmed by further expe- 

 riments. In that light, he himself evidently first viewed 

 it ; thus, in his letter to Dr Priestley, of the 21st of April 

 1783, he says, " On considering your very curious and im- 

 portant discoveries on the nature of phlogiston and dephlo- 

 gisticated air, and on the conversion of water into air, and 

 vice versa, some thoughts have occurred to me on the pro- 

 bable causes of these phenomena, which, though they are 

 mere conjectures, seem to me more plausible than any I have 

 heard on the subject, and, in that view, I have taken the li- 

 berty to communicate them to you." And he concludes the 

 same letter with this remark, — " If you shall think that a 

 hypothesis so hastily compiled, deserves to have the honour 

 of being communicated to the Royal Society, or published in 

 any other way, with the account of your experiments, I shall 

 be obliged to you to present it to the Society, or to the 

 public, as you shall think proper." Again, in his letter 

 to Sir Charles Blagdon respecting the publication of his 

 paper (his letter to M. de Luc), he says, — " I am really 

 at a loss what title to give the paper ; but propose the 

 following, — conjectures — Thoughts on the constituent parts 

 of water, and of dephlogisticated air, with an account of 

 some experiments on that subject." And, in his letter to 

 M. de Luc, ho prefaces it with the remark, " I feel much 



