114 Rev. W. V. Harcou It on Lord Brougham's statements 



was now received and adopted by almost every chemist." A 

 detailed account is then given of Cavendish's experiments ; 

 and it is added, "these experiments were made in 1781, and 

 they are undoubtedly conclusive of the composition of water. 

 It would appear that Mr. Watt entertained the same ideas on 

 this subject. When he was informed by Dr. Priestley of the 

 result of these experiments, he observed, Let us consider 

 what obviously happens in the deflagration of oxygen and hy- 

 drogen gases," &c. "Thus it appears that Mr. Watt had a 

 just view of the composition of water, and of the nature of the 

 process by which its component parts pass to a liquid stale from 

 that of an elastic fluid." 



In this account the ideas entertained by Mr. Watt obtain more 

 notice perhaps than would have been accorded to them by anin- 

 different historian; but the statement of the discovery is correct, 

 as is also that of the view which Watt took of the subject, if we 

 confine the assertion of the justness of his ideas to his appre- 

 hension of the relation of Cavendish's discovery to certain 

 theories of light and heat ; for of the material base of water he 

 had certainly no just conception when he wrote the letter 

 which is quoted above. I have shown that his views in 1783 

 and 1784 were founded on several suppositions: — 1st, that 

 Priestley had converted water into atmospheric air; 2nd, that 

 he had obtained a weight of water equal to the weight of a 

 mixture of oxygen with the gases extricated by heat from moist 

 charcoal', 3rd, that he had shown good reason to believe that 

 carbon, combined in a certain proportion with oxygen, con- 

 stitutes water. All these suppositions agreed perfectly with 

 the opinions which Watt really expressed, that water was 

 formed of dephlogisticated air and phlogiston ; but no one of 

 them is consistent with the opinions attributed to him by an 

 erroneous translation of his words, that water is formed by the 

 combination of oxygen with hydrogen gas*. 



From your mention of Sir H. Davy's sentiments without a 

 quotation, I suppose that he, like Dr. Henry, has been among 

 the number of those on whose attention this untenable claim 

 has been privately pressed ; all I know of Davy's opinion on 

 the subject is from his published works, in which he has spoken, 

 like other chemists, of the composition of water and of nitric 

 acid as " the two grand discoveries of Mr. Cavendish." But in 

 referring to the name of this much-honoured and regretted 

 friend, I must take the opportunity of noticing what I think a 

 serious error in your impressions respecting one point in his 

 personal character. You begin your sketch of his life with these 

 words: "Sir H.Davy being now removed beyond the reach of 

 * See Report of the British Association for 1839, pp. 24, 25. 



