22 2 Of the Light manifested in Combustion. 



under it in such a manner that the point of its flame 

 was on a level with the under side of the wooden per- 

 forated stand on which the boiler reposed. 



This candle had burned very equally and very quietly 

 just 12 minutes and 30 seconds, when I observed by 

 the thermometer that the water had acquired the tem- 

 perature of 75° F. The candle was immediately extin- 

 guished, and on weighing it I found that 1.62 grammes 

 (= 25.02 grains Troy) of wax had been consumed in 

 this experiment. 



The difference between the quantities of wax con- 

 sumed in these two experiments in communicating 

 the same quantity of heat to the same quantity of cold 

 water is very small, amounting to only about one grain 

 and a half Troy, and may easily be accounted for in 

 a satisfactory manner, without having recourse to the 

 very improbable supposition that the heat may per- 

 haps be variable that accompanies the combustion of 

 the same inflammable substances. 



The light which accompanies that process is most 

 certainly variable, and that to a very surprising 

 extent. 



The results of these experiments are very interesting, 

 and the more attentively we examine the new facts with 

 which they make us acquainted, the more clearly we 

 shall perceive their importance. 



They will make us better acquainted with light, and 

 also with heat, and will assist us in distinguishing and 

 appreciating their effects. 



As long as the doctrine which supposes light to be 

 a substance emitted by luminous bodies continues to 

 be believed and universally taught, a great deal of 

 time will no doubt continue to be employed in useless 



