Lord Brougham on the Composition of JFater. 323 



de TAcademie, though his own account of that experiment^ and of what 

 then passed, is inconsistent with Sir Charles Blagden's statement.* 



But, there is not any assertion at all even from Sir C. Blagden, zealous 

 for Mr Cavendish's priority as he was, that Mr Watt had ever heard of 

 Mr Cavendish's theory before he formed his own. 



Whether or not, Mr Cavendish had heard of Mr Watt's theory previous 

 to drawing his conclusions, appears more doubtful. The supposition 

 that he had so heard, rests on the improbability of liis (Sir Charles Blag- 

 den's), and many others knowing what Mr Watt had done, and not com- 

 municating it to Mr Cavendish, and on the omission of any assertion in 

 Mr Cavendish's paper, even in the part written by Sir C. Blagden with 

 the view of claiming priority as against Mr Lavoisier, that Mr Caven- 

 dish had drawn his conclusion before April 1788, although, in one of the 

 additions to that paper, reference is made to Mr Watt's theory. 



As great obscurity hangs over the material question at what time Mr 

 Cavendish first drew the conclusion from his experiment, it may be as 

 well to examine what that great man's habit was in communicating his 

 discoveries to the Royal Society. 



A Committee of the Roj-al Society, with Mr Gilpin the clerk, made a 

 series of experiments on the formation of nitrous acid, under Mr Caven- 

 dish's direction, and to satisfy those who had doubted his theory of its 

 composition, first given accidentally in the paper of January 1784, and 

 afterwards more fully in another paper, June 1785. Those experiments 

 occupied from the 6th December 1787 to 19th March 1788, and Mr Ca- 

 vendish's paper upon them was read l7th April 1788. It was there- 

 fore written and printed within a month of the experiment being con- 

 cluded. 



Mr Kirwau answered Mr Cavendish's paper (of 15th January 1784) 

 on water, in one which was read 6th February 1784, and Mr Cavendish 

 replied In a paper read 4th March 1784. 



Mr Cavendish's experiments on the density of the earth, were made 

 from the 5th August 1797 to the 27th May 1798. The paper upon that 

 subject was read 27th June 1798. 



The account of the eudiometer was communicated at apparently a 

 greater interval ; at least the only time mentioned In the account of the 

 experiments is the latter half of 1781, and the paper was read January 

 1783. It Is, however, probable from the nature of the subject, that he 

 made further trials during the year 1782. 



That Mr Watt formed this theory during the few months or weeks 

 immediately preceding April 1783 seems probable.t It is certain that 



" Could Blagden'H letter to Crell also have escaped Lavoisier's notice ? 

 [Note by Mr James AVatt.] 



+ That the idea existed in his mind previously, is proved by his declarations 

 to Dr Priestley, cited by the latter; by his own assertions, p. 335 of his paper, 

 and by the existing copies of his letters in 1782. [Note by Mr Jamks Watt.] 



