NOTES. 477 



the name, among the very first in all sciences, of Cuvier, we 

 may at once wonder and mourn. 



Since the Life of Watt was published, a very strange 

 attack on both M. Arago and myself, but more especially 

 on my illustrious colleague, has appeared in the ' Quarterly 

 Review.' The ingenious and (as far as this controversy is 

 concerned) not very learned critic appears to be led away 

 by the excess of his zeal for Mr. Cavendish. I leave him 

 in the hands of M. Arago, who will observe with some 

 wonder that he has been accused and judged and condemned 

 by a chemist so well versed in that science, and so reflecting, 

 as to announce the astonishing novelty, that the exhibition 

 of sulphur to sulphuric acid reduces that acid and restores 

 it to its primitive state of sulphur ! The writer had pro- 

 bably read somewhere that sulphuric acid is reduced to sul- 

 phurous by the process ; for he is assuredly the first that 

 had ever hit upon the acid's reduction by sulphur " to its 

 primitive state."* I have lying before me fifteen pages of 

 statements of chemical errors in the thirty-four pages of 

 the paper ; and as these are the work of a most experienced 

 and learned and practical chemist, whom I consulted on the 

 above and other parts of the paper, I have entire reliance 

 on his report and opinion. I must also add that he com- 

 pletely bears out, by the authority of his concurring opinion, 

 the statements (disputed by the critic) which I had ven- 

 tured to make respecting Dr. Black's discoveries, with the 

 single exception that he is not aware how far I am justified 

 in stating the greater specific gravity of fixed air as known 

 to him before Mr. Cavendish's experiments in 1766. My 

 reason for so stating was my distinct recollection of Dr. B. 

 having in his lectures shown us the experiment of pouring 

 fixed air out of a receiver on a candle, and his having given 

 this as a property originally known to himself when he dis- 

 covered the gas, though it is very true that the published 

 lectures do not decide either way the question of his early 

 knowledge. His not mentioning Mr. Cavendish or any one 



* The process of reducing phosphoric acid to its primitive phosphorus, 

 had just been stated, and the writer adds, " A similar succession of pheno- 

 mena are presented by sulphur, &c. ;" and he enumerates sulphur as one of 

 the bodies which reduce the acid to its primitive state. 



