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FLAME. 



Flame is considered as the most perfect modification of combus- 

 tion, that is to say, gaseous bodies, in combustion combine 

 with more avidity, and produce a much higher temperature, than 

 solid bodies. 



The principal properties recognised in gaseous combustion, or 

 as it has been termed. Flame, are heat and light — and it will be 

 the object of the following remarks, to endeavour to explain or 

 investiojate some of the causes which produce and modify these 

 appearances. 



On examining the flame of any burning body, it appears to 

 consist of two parts ; first, a white cone of bright light, and 

 secondly, an outer casing of faint red light, producing intense 

 heat. Some have included the dark hollow centre of the flame 

 as a third part, but rather improperly, since the term flame can 

 only be applied to those parts where combustion is immediately 

 going on. On examining the properties of these two portions of 

 the flame, they are found to differ considerably. The inner one, 

 or that from which the light proceeds, gives out, comparatively, 

 but little heat ; — whilst the outer thin film, the light of which is. 

 almost eclipsed by the brilliancy of the other, is found to produce 

 a very intense degree of heat. 



The writer is induced to suppose, that light is not an essen- 

 tial product of combustion. That it always accompanies gaseous 

 combustion cannot be denied ; but this appears to arise from the 

 admixture of heterogeneous solid matter, either in the atmosphere 

 or in the gaseous matter, undergoing combustion ; and there is 

 every reason to suppose, that if by any means the presence of 

 these solid particles could be prevented, gaseous bodies would 

 combine, and produce heat without light. 



The light given out by flame appears to depend upon two 

 causes: first, the quantity of solid matter contained in it and 

 ignited, and, secondly, the heat producing this ignition. 



Attempts have been made to show that light and heat, and 

 heat and light are in an inverse ratio : but this, on examination, 

 will be found to be erroneous ; for although there are many cases 

 in which much heat is produced, with very little light, in conse- 

 quence of the paucity of solid matter; still there are otlier cases 

 where solid matter is present in which both light and heat are 

 extremely feeble. For example — carbonic oxide burns with a 

 lambent blue flame, and produces but very little heat. The heat 



