Royal Institution. 305 



ROYAL INSTITUTION. 



Mr. Brande's seventh lecture related exclusively to the disco- 

 veries of Mr. Cavendish, and to the state of chemical philoso- 

 phy at the period at which he terminated his successful career. 



Although Van Hehnont, Mayow, and others were acquainted 

 with inflammable gaseous fluids, the nature of the principle upon 

 which their inflammability depended had been but very imper- 

 fectly guessed at, till iVIr. Cavendish turned his mind to the 

 subject, and published upon it in the Philosophical Transactions 

 for 1766. The nature and pioperties of inflammable air are 

 there dwelt upon with a masterly perspicuity, and its leading 

 peculiarities particularly developed. 



That the combustion of a mixture of this air with common 

 air produced moisture or dew, had been observed Ijy Macquer, 

 Priestley, and others; but its source was hidden until exposed by 

 the acute suggestion of Mr. Watt, and the decisive experiments 

 of Mr. Cavendish, who burned by means of the electric spark a 

 mixture of two measures of inflammable air, and one of dephlo- 

 gisticated air, and obtained an equivalent weight of pure water : 

 thus was the composition of this universal fluid (till then deemed 

 elementary) demonstrated with an exactness and precision of 

 which chemists had hitherto had no example. 



Mr. Brande said, that the subject upon which he was then 

 engaged was of such consequence in the history of the French 

 chemical revolution, of which he should consider the merits 

 and demerits in his next lecture, that it would be proper to ex- 

 hibit a few analytic proofs of the correctness of Mr. Cavendish's 

 general views. The decomposition of steam by red hot iron, and 

 of water by the galvanic battery, were then shown. 



Several singular properties of kydrogen, or inflammable air, 

 were illustrated ; especially the production of musical tones by 

 the combustion of the gas in tubes of different diameters and 

 materials. 



Having noticed Mr. Cavendish's second great discovery, that 

 of the composition of nitric acid, the Professor entered at some 

 length into the discussions which had arisen concerning the 

 identity of hydrogen and phlogiston, and showed, by several ap- 

 posite exjjeriments, the additional strength and probability which 

 the phlogistic hypothesis had attained in consequence of the dis- 

 covery of inflammable air: he said that, in treating of the anti- 

 phlogistic doctrines, he should draw a comparison between the 

 facts upon which they are founded, and those v/hich support 

 iStahl's notions. Having put his audience in possession o^ Mr. 

 CavendisH's principal discoveries, Mr. Brande digressed shortly 



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