and the Economy of Fuel. 59 



ner in which heat is communicated to bodies by flame, 

 I made the following experiments, the results of which 

 I conceive to be decisive. 



Concluding that the current of air from a blowpipe, 

 directed against the flame of any burning body, could 

 tend to increase the intensity of the action of the flame 

 only in one or both of these two ways, namely, by 

 increasing its action upon the body against which it is 

 directed, or by actually increasing the quantity of heat 

 generated in the combustion of the fuel, a method 

 occurred to me by which I thought it possible to deter- 

 mine, by actual experiment, to which of these causes 

 the effect in question is owing, or how much each of 

 them might contribute to it. To do this, I filled a large 

 bladder, containing above a gallon, with fixed air, which, 

 as is well known, is totally unfit for supporting the com- 

 bustion of inflammable bodies, and which, of course, 

 could not be suspected of adding any heat to a flame 

 against which a current of it should be directed. I 

 imagined therefore that if a blowpipe supplied with 

 this air, on being directed against the flame of a can- 

 dle, should be found to produce nearly the same effect 

 as when common air is used for the same purpose, it 

 would prove to a demonstration that the augmentation 

 of the intensity of the action, or activity of the flame 

 which arises from the use of a blowpipe, is owing to 

 the agitation of the flame, to its being directed to a 

 point, to the impetuosity with which it is made to 

 strike against the body which is heated by it, and 

 to the rapid succession of fresh particles of this hot 

 vapour, and not to any positive increase of heat. 



A blowpipe being attached to the bladder containing 

 fixed air, the end of this pipe was directed to the clear 



