Of the Light manifested in Combustion. 211 



ought to be considered as a demonstrative proof of the 

 fallacy of that hypothesis. 



Both the size and the form of a flame must neces- 

 sarily have so much influence on the celerity of the 

 cooling of the particles of which it is composed that, if 

 it should be found that neither of these circumstances 

 has any sensible influence on the quantity of light 

 which it diffuses, this fact must be considered as a 

 proof that the light does not depend entirely on the 

 preservation of the heat of the flame, in the manner 

 above described. 



But if, on the other hand, it should be found from 

 the results of decisive experiments that the light which 

 accompanies the complete combustion of any given 

 quantity of pure inflammable matter should be vari- 

 able, it will be impossible, I imagine, not to perceive 

 that that light cannot be one of the chemical products of 

 combustion ; and that the hypothesis which supposes 

 light to be a substance emitted by luminous bodies 

 must become more and more difficult to support. 



If the question in dispute respecting the nature of 

 light were merely speculative, and could never have 

 any influence either on the progress of science or on 

 the improvement of the useful arts, I should be the 

 first to condemn this discussion, not only on account 

 of its being useless, but also, and more especially, on 

 account of the disagreeable consequences to society 

 which always must result from disputes of that kind. 

 But the subject under consideration is very far indeed 

 from being uninteresting. To see the importance of 

 it, we have only to consider for a moment the vast 

 advantage to society that could not fail to result from 

 the discovery of any fixed principle that could be 



