314 Additional Notes to 



But as far as the French chemists are concerned, M. Arago's statement 

 is literally true. Fourcroyj in his voluminous work, " Systeme des Con- 

 naissances Chimiques," published in 1801, appears studiously to have 

 avoided the very mention of Mr Watt's name, although he could not but 

 be acquainted with his paper in the Philosophical Transactions for 1784, 

 and had seen him at Paris in 1787, in the society of his friends Berthollet, 

 Laplace, Mongc, and Lavoisier, by all of whom Mr Watt's merits were 

 appreciated. Ouvier, probably misled by this authority, gives the disco- 

 very to Cavendish and Monge, at p. 67 of his " Rapport Historique sur 

 les Progres des Sciences Naturelles," which was presented to Napoleon 

 by the Institute in 1808, as well as in his Eloge of Fourcroy, read 1811, 

 and of Cavendish, read 1812. 



We take this opportunity of noticing that the writer of the life of Watt 

 in Brewster's Encyclopsedia, so late as 1830, has made assertions favour- 

 able to Cavendish's claims, founded on a perusal of the papers he has 

 left. His Grace the Duke of Devonshire, as the representative of Mr 

 Cavendish, granted permission to examine these papers. This was done 

 by those eminent chemical philosophers, Mr Charles Hatchett and Mr 

 Brando, who found nothing in them confirmatory of Mr Cavendish's 

 claims to the priority of the theory, which rests, as before, on the publish- 

 ed papers of Mr Cavendish, Mr Watt, and Sir C. Blagden. 



Warltire (p. 269.) M. Arago has omitted to state, that Mr Warltire, 

 in his letter dated Birmingham 17th April 1781, after relating his own 

 experiments in the metal globe, goes on to say, " I have fired air in 

 glass vessels since I saw you" [Dr Priestley] " venture to do it, and 

 have observed, as you did, that though the glass was clean and dry 

 before, yet after firing the air it became dewy, and was lined with a 

 sooty substance." This proves Dr Priestley to have first made the ex- 

 periment in glass vessels, as well as to have first noticed the dewy de- 

 posit. 



" Letter from Watt to Dehic." — (p. 270.) See Phil. Trans, vol. Ixxiv. 

 p. 330, and particularly Mr Watt's note at the foot of that page. The 

 note is as follows : — " This letter Dr Priestley received at London, and 

 after shewing it to several members of the Royal Society, he delivered it 

 to Sir Joseph Banks the President, with a request that it might be read at 

 some of the public meetings of the Society ; but before that could be 

 complied with, the author, having heard of Dr Priestley's new experi- 

 ments, begged that 'he reading might be delayed. The letter, therefore, 

 was reserved until the 22d of April last [1784], when, at the author's re- 

 quest, it was read before the Society. It has been judged vmnecessary 

 to print that letter, as the essential parts of it are repeated, almost ver- 

 hatim, in this letter to M. Deluc ; but, to authenticate the date of the 

 author's ideas, the parts of it which are contained in the present letter 

 are marked with double commas." 



" Une quantite d' eau tres sensible." — (p. 271.) Lavoisier's paper, in which 

 these words occur, appears at p. 472 of that volume of the " Memoires 



