on Combustion and Flame. 87 



treatises on chemistry ; an excellent account of them may be 

 found in Ure's Chemical Dictionary, under the article Com- 

 bustion. The subject however is not exhausted, and there 

 are still some questions which- by a new method of investiga- 

 tion may I think now be decided, and several phaenomena 

 hitherto unaccounted for which may now be explained. 



The principal or essential circumstance in combustion is 

 the fact of combination between two substances of opposite 

 electrical energies. One of these, as being the apparent source 

 of the heat and light, is called the combustible ; the other, as 

 absolutely necessary to the phaenomena, the supporter of 

 combustion. This has given rise to the division of bodies 

 into these two classes, supposed by some to be remarkably 

 distinguished from each other by their part in the process as 

 they are in their place on the electro-chemical scale. Others 

 again have contended that there is no essential distinction be- 

 tween the two classes of bodies with respect to this phaeno- 

 menon ; that in fact both are equally entitled to the name of 

 combustible, and that the heat and light evolved are simply 

 indications of energetic chemical action between any two sub- 

 stances : in proof ol" this various instances have been adduced, 

 such as the combustion which takes place between iron or 

 copper filings and sulphur, between potassium and cyanogen 

 or sulphuretted hydrogen, between vapour of anhydrous sul- 

 phuric acid and dry baryta, as noticed by Bussy, magnesia and 

 sulphuric acid, &c. in all of which we have all the phaeno- 

 mena of combustion, without the presence of any of those 

 substances exclusively called supporters of combustion, or 

 in some of these cases without either combustibles or sup- 

 porters. 



The latter explanation seems now to be admitted so far by 

 chemists in general, but yet it occurred to me that its truth 

 was susceptible of still better demonstration, and that instead 

 of searching for particular instances of combustion it might 

 be supported by a much more general proposition : that in 

 fact if this were the true explanation, it should follow as a ge- 

 neral rule, that if what is commonly called a combustible burn 

 in a supporter, a supporter ought also to burn in a com- 

 bustible. This accordingly on trial I found to be the case. 



The apparatus employed for these experiments consisted 

 of a wide-mouthed flask (about 8 or 9 inches long) having 

 cemented to it a cap of tinned iron, pierced with four holes : 

 to two of these two brass sockets were soldered, made to fit 

 the ends of two flexible tubes proceeding from two gas- 

 holders ; to the two other holes were attached small pieces 

 of tube, over one of which a piece of sheet caoutchouc was 



