CAVENDISH. 97 



friends, fellow-members of the Royal Society; and 

 after some weeks of constantly passing the electric 

 fluid through a limited portion of air, a small quantity 

 of liquid was formed, which readily combined with a 

 solution of potash in water sent up through the mer- 

 cury. This union was found to be common nitre, 

 having all the qualities of that well-known substance. 

 It detonated with charcoal ; it sparkled when paper 

 impregnated with it was burnt; it gave out nitrous 

 fumes when sulphuric acid was poured on it. There 

 could, therefore, no doubt whatever now exist that 

 nitrous acid is composed of the two airs deprived of 

 latent heat, which form our atmosphere ; that it is a 

 true oxide of azote. 



The undivided merit of this important discovery has 

 never been denied to Mr. Cavendish. Even Lavoisier 

 could not intrude ; but his avidity to claim a share in 

 all discoveries had been exerted respecting the com- 

 position of water, which he asserts in his ' Elements of 

 Chemistry' to have been discovered by himself and 

 Mr, Cavendish about the same time. I have shown 

 clearly in the Appendix to the Life of Mr. Watt, that 

 the discovery had been previously communicated to 

 the French philosopher ; but it is worth while to con- 

 sider the experiment upon which he grounded his 

 claim ; and that experiment, when examined, is found 

 wholly insufficient to prove the position, even if it had 

 been contrived and performed before the communica- 

 tion of Watt's and Cavendish's discovery. Of that 

 discovery it was plainly a corollary by that discovery 

 it was manifestly suggested. 



The former experiments, both those of Cavendish 

 and those on which Watt reasoned, were all syntheti- 

 cal and decisive that of Lavoisier was analytical and 

 radically defective. It proved nothing conclusively : 

 it was well enough after the experimentum crucis had 

 demonstrated the proposition ; to that proposition it 

 was a corollary it was nothing like a critical experi- 



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