Discovery of the Composition of Water. 43 



intention is most fully displayed, and in a manner, it appears 

 to me, characteristic of the advocate— the special pleader 

 rather than of the man of science— in the manner of one 

 anxijaus to gain a verdict in favour of his client, rather than 

 intent on dispassionate inquiry; and often, in accordance with 

 forensic practice, using damaging expressions of an offensive 

 kind, which never would have been employed in liberal and 

 courteous discussion. 



It is not my intention to enter into any lengthened com- 

 mentary on this work (a quarto of 391 pages). After having 

 carefully read it, I have found no reason to alter the opinion 

 which I had previously formed and expressed, viz. that Mr 

 Watt and Mr Cavendish independently arrived at the idea, 

 or inference, that water is the compound it is now considered, 

 —a conclusion, I have said, alike honourable to Mr Watt 

 and to Mr Cavendish, and which is free from all the difficul- 

 ties and painful consequences connected with the contrary.* 

 Such was my first impression, and thus has it been con- 

 firmed. The facts on which it was founded are principally 

 the following, as then stated :— Dr Priestley, in his paper 

 " On the seeming Conversion of Water into Air," bearing date 

 Birmingham, April 21, 1783, distinctly mentions "an experi- 

 ment of Mr Cavendish, concerning the reconversion of air into 

 water, by decomposing it, in conjunction with inflammable 

 air,"t a result which he confirmed by repetition. This result, 

 derived or learnt from Dr Priestley, was the basis, it would 

 appear, of Mr Watt's hypothesis respecting the nature of wa- 

 ter, as stated by him to M. de Luc, and also the true basis of 

 that hypothesis, as given in his earlier letter to Dr Priestley. J 



* Collected Works of Sir H. Davy, vol. vii., p. 133. 



t Dr Priestley's words are,—" Still hearing of many objections to the con- 

 version of water into air, 1 now gave particular attention to an experiment of 

 Mr Cavendish's, concerning the reconversion of air into water, by decompos- 

 ing? it in conjunction with inflammable air."— P/i?7. Trans, for 1783, p. 426. 



\ Mr Watt, referring to Dr Pripstley's experiment on the firing of a mixture 

 of dephlogislicated air (oxygen) and inflammable air, and the production of 

 moisture, states, in a note,—" I believe that Mr Cavendish was the first who 

 discovered that the combustion of dcphlogisticated and inflammable air pro- 

 duced moisture on the s-idcs of the glass in wliich thoy were fired." Mr Caven- 



