and the Economy of Fuel. 61 



pheric air, and at other times using dephlogisticated air, 

 and common air rendered unfit for the support of ani- 

 mal life and of combustion, by burning a candle in it 

 till the candle went out. 



It would take up too much time to give an account 

 in detail of all these experiments. I shall therefore 

 content myself with merely observing that they all 

 tended to show that the effect of a blowpipe used in 

 the manner here described is owing to the direction and 

 velocity it gives to the flame against which it is em- 

 ployed, and not to any real increase of heat. 



It must be remembered that the principal object I 

 had in view in these experiments was to discover the 

 manner in which flame communicates heat to other 

 bodies, and by what means that communication may be 

 facilitated. Were it required to increase the intensity 

 of the heat by blowing the fire, the current of air must 

 be applied in such a manner as to expedite the com- 

 bustion : it must be directed to the inflamed surface of 

 the burning fuel, and not to the red-hot vapour or flame 

 which rises from it, and in which the combustion is 

 most probably already quite complete ; and in this case 

 there is no doubt but the effect produced by blowing 

 would depend much upon the quality of the air made 

 use of. 



The results of the foregoing experiments with the 

 blowpipe will, I am confident, be thought quite conclu- 

 sive by those who will take the trouble to consider them 

 attentively; and the advantages that may be derived 

 from the knowledge of the fact established by them are 

 very obvious. If flame, or the hot vapour which arises 

 from burning bodies, be a non-conductor of heat ; and 

 if, in order to communicate its heat to any other body, 



