HISrORT of the SOCIE-rr. rj 



without flame, and burning with flame ; that is, on the pheno- 

 mena of combuftion and inflammation. 



In the combuftion of a piece of charcoal, two diflindl effedt. 

 may be traced, viz. i. The oxygenating of the carbonic fub- 

 ftance, by which fixed air is produced, or carbonic acid in an 

 elaftic ftate ; 2. The produdlion of a great quantity of hght 

 and heat, while the charcoal is undergoing this change. It is 

 with refpe<fl to this laft part of the procefs only that different 

 opinions are entertained. The phlogiftic theory maintains, that 

 in the oxygenation of the carbonic fubftance by the. vital air, 

 the phlogiftic matter of that fubftance is fet free from combi- 

 nation with it, and in making its efcape exhibits the phenomena 

 of light and heat. 



The antlphlogiftig theory, on the other hand, fuppofes, that, 

 by the decompofition or the condenfation which the vital air 

 undergoes, while it oxygenates the carbonic fubftance, the la- 

 tent heat is transferred to that fubftance, and produces light and 

 foe* 



Now, if it can be fliewn that a burning coal, though placed 

 i-n circumftances the moft favourable for its oxygenation, may 

 Jjteverthekfs lo.fe its heat, and ceafe to burn entirely, it is cer- 

 tain, that it is not aloiie by the calorique of the vital air that the 

 j^re is fupported. Let then a confolidated piece of charcoal, fuch 

 :^-s the niiueral kingdom, in many places, affords in great perfec- 

 tion, be lieated to the higheft degree of incandefcence, and 

 expofed, infulated, to the atmofpheric air. Here every condi- 

 tiop, is united favourable to the oxygenation of the coal, a fuf- 

 jRqient quantity of heat;, aad free accefs of air. If the heat, fup- 

 pli«d from the decompoflcion of tlie vital air, were able to main- 

 tfiip. the heat of the coal, it would continue to burn ; but the 

 fadl is, that, in fuch a fitiiatlon as is here defcribed, the coal 

 J^s, it^ hy^^tj. and it is at 1^ extinguxfhe,d. Lt is plain, there- 



