426 Rev, Mr. Emmett en Combmtion. [Dec. 



of M. Balard is extremely well drawn up, and the numerous 

 results which he relates would not fail to excite great interest, 

 even if it should be proved that brome is not a simple body. 



The discovery of brome is a very important acquisition to 

 chemistry, and gives M. Balard honourable rank in the career 

 of the sciences. We are of opinion that this young chemist is 

 every way worthy of the encouragement of the Academy ; and 

 we have the honour to propose that his memoir should be printed 

 in the Recueil des Savaiis Etrangers, 



Signed VAUQUhLiN, Thenard, G a y-Luss a c, Reporter. 



The Academy adopts the conclusions of this Report. 



Article V. 



On Combustion* By the Rev. J. B. Emmett. 

 (To the Editors of the Annals of Philosophy.) 



GENTLEMEN, Great Ouseburn, Nov. 15, 1826. 



The fact has long been established, that when condensation 

 takes place during chemical combination, heat is evolved;* 

 sometimes the quantity is so small as to be barely sensible ; at 

 others, intense heat is excited, accompanied with emission of 

 light. The old chemists, supposing atmospheric air to be an 

 elementary substance, and finding its presence essential to what 

 is ordinarily termed combustion, gave the name of inflammable 

 bodies to those substances which emit both light and heat 

 when exposed to the air at an elevated temperature ; and 

 although cases where both light and heat are abundantly united 

 during combination, where air is excluded, and is indeed unes- 

 sential, are very numerous, yet they limited the signification of 

 the term combustion to those cases which can take place only 

 by the agency of air,f which, in the language of modern che- 

 mistry, was supposed to be the only " supporter of combustion." 

 When the science of chemistry was reformed by the French 

 philosophers, since the atmosphere was then known to be a 

 mixture;}: of two gaseous bodies, of which, that which consti- 



♦ If any volume of water be mixed with an equal one of the sulphuric acid of com- 

 merce, a great degree of heat is excited ; when the mixture becomes cool, it will not 

 occupy the measure of two volumes. Nitric acid excites less heat, and the union is 

 attended with less considerable condensation. When water and alcohol are mixed, both 

 effects are witnessed in a smaller degree. The law extends to all classes of bodies. 



+ This limitation is strictly proper in the ordinary affairs of life ; for inasmuch as 

 "both life and fire are supported solely by the atmosphere, it is tlie sensible and obvious 

 supporter of combustion. 



Ij: A mixture, because by mixing the proper proportions of oxygen and azote, a com- 

 pound resembling atmospheric air is produced (except that the small proportion of car- 

 bonic acid gas, aqueous vapour, and minute quantities of some other gaseous bodies, are 

 wanting), yet neither expansion, compression, heat, cold, ox any other gymptom of 



