^Ti HISTOEY OF CHEMISTRY. 



that when inflammable air is used in this phlogistication (or burning), 

 the diminution of the common air is accompanied 'by the formation of 

 a dew in the apparatus. 8 And thus he infers" that "almost all the 

 inflammable air, and one-fifth of the common air, are turned into pure 

 water." 



Lavoisier, to whose researches this result was, as we shall soon see, 

 very important, was employed in a similar attempt at the same time 

 (1783), and had already succeeded, 7 when he learned from Dr. Blagden, 

 who was present at the experiment, that Cavendish had made the 

 discovery a few months sooner. Monge had, about the same time, 

 made the same experiments, and communicated the result to Lavoisier 

 and Laplace immediately afterwards. The synthesis was soon 

 confirmed by a corresponding analysis. Indeed the discovery undoubt- 

 edly lay in the direct path of chemical research at the time. It was of 

 great consequence in the view it gave of experiments in composition ; 

 for the small quantity of water produced in many such processes, had 

 been quite overlooked ; though, as it now appeared, this water offered 

 the key to the whole interpretation of the change. 



Though some objections to Mr. Cavendish's view were offered by 

 Kirwan, 8 on the whole they were generally received with assent and 

 admiration. But the bearing of these discoveries upon the new theory 

 of Lavoisier, who rejected phlogiston, was so close, that we cannot fur- 

 ther trace the history of the subject without proceeding immediately 

 to that theory. 



[2nd Ed.] [I have elsewhere stated, 9 with reference to recent 

 attempts to deprive Cavendish of the credit of his discovery of the 

 composition of water, and to transfer it to Watt, that Watt not only 

 did not anticipate, but did not fully appreciate the discovery. of Caven- 

 dish and Lavoisier; and I have expressed my concurrence with Mr. 

 Vernon Harcourt's views, when he says, 10 that " Cavendish pared off 

 from the current hypotheses their theory of combustion, and their affi- 

 nities of imponderable for ponderable matter, as complicating chemical 

 with physical considerations; and he then corrected and adjusted then: 

 with admirable skill to the actual phenomena, not binding the facts to 

 the theory, but adapting the theory to the fact's." 



I conceive that the discussion which the subject has recent'y received, 

 lias left no doubt on the mind of any one who has perused the docu- 



Phil. Trans. 1784, p. 128. 6 Ib.p.l29. T A. P. 1781, p. 472. 8 P. T. 1784, p. 154 

 Philosophy, b. vi. c. 4. 10 Address to the British Association, 1839. 



