SOf! Proacdings of Philosophical Societies. [Oct. 



which Dr. Wells lias affixed to this. I have frequently in writing 

 or speaking on the subject found the inconvenience of such a want, 

 and was obliged to have recourse to the disagreeable mode of ex- 

 pressing my meaning by a circumlocution. Whether the word 

 conduction be the most proper for the purpose must be left to the 

 decision of British philosophers in general. For my own part, I see 

 »o objections to the term, and should not scruple to employ it 

 when writing upon heat. 



Article XVI. 



Proceedings of Philosophical Societies. 



IMPERIAL INSTITUTE OF FRANCE. 



Anoxmt of the Labours of the Class of Mathematical and Physical 

 Sciences of the Imperial Institute of France during the Year 1813. 



(Continued from p. 230.) 



Physics and Chemistry. By M. le Chevalier Cuvier. 

 It is supposed that the combinations which exist commonly in 

 nature are those to which the great affinity between their consti- 

 tuents give a certain stability, and which circumstances by no means 

 common have the power to decompose ; while those which do not 

 possess that property can only be momentary and accidental pro- 

 ductions, or obtained by the labours of chemists. The greater 

 number of the former are discovered, the more fugitive ought those 

 to be which remain to be discovered, and the more subject to be 

 destroyed by the least accidental circumstance. This is what has 

 occasioned the accidents of which the history of chemistry offers so 

 many examples, and against which the more precautions ought to 

 be taken the more difficult and delicate the researches are in which 

 the chemist is engaged. 



M. Dulong, Professor of Chemistry at Al fort, was on the point 

 last year of becoming a victim to his zeal for the science. But his 

 danger was recompensed by a fine discovery — a compound of azote 

 and oxymuriatic acid, which presents the most singular properties. 

 To obtain it we must present to the chlorine, as the British chemists 

 at present term it, azote not in the state of gas, but in any combi- 

 nation. Any ainmoniacal salt will answer, provided the acid which 

 it contains be not driven oft* by the chlorine. M. Dulong passes a 

 current of chlorine through the solution of such a salt, and obtains 

 a kind of brown oil, heavier than salt water, which is quickly 

 dissipated in the open air, and detonates when heated with a report 

 louder than a musket. Copper decomposes it, uniting with the 

 chlorine, and disengaging azotic gas. Hence we see its constituents. 



