294 Messrs. B. Silliman and H. Wurtz on Flame Temperatures, 



a number which, we may add, represents the maximum of heat 

 capable of being imparted to liquid water by the flame of Hare's 

 oxyhydrogen blowpipe. 



Still we have by no means here the actual temperature of the 

 free or open flame of Hare's blowpipe, which is generally lower 

 than this figure, as we have not yet taken into account the 

 " latent heat," or heat of vaporization, of the 9 lbs. of steam 

 formed. The Centigrade temperature necessary to convert 1 lb. of 

 water into steam being 537°, to get the actual temperature of the 

 oxyhydrogen flame we must modify the above equation, so that 



a= 34462°-(9x537°) =685l0 Q=1X p . 

 4*o<^45 



which is the temperature actually possible in the flame of the com- 

 pound blowpipe, were the combustion instantaneous and complete. 

 When hydrogen gas burns in air, however, as has been before 

 stated, another deduction of enormous amount must be made 

 from the above figures, due to the heat required to expand the 

 nitrogen. This is obtained simply by adding to the divisor, as 

 above, the weight of the nitrogen of the air employed, multiplied 

 by its specific heat. The weight of the nitrogen in air =3*318 

 times the oxygen, so that the latter of the above equations 

 becomes 



34462°- (9x537°) _ gni o. 5 c _ 4972 o F 



x - 4-3245 + (8 x 3-318 x 0-2438) ~ Z74A 5 U_ m ™ *' 



We have here a full explanation of the extraordinary rate of 

 degradation of illuminating gas by admixture of air, which we 

 have discussed elsewhere. The nitrogen of such air is not merely 

 a diluent or even a mere deductive quantity, its specific heat is 

 an actual divisory function in diminishing the flame-temperature. 



This, then, is the actual temperature to which the flame of 

 hydrogen gas burning in the atmosphere might attain to, sup- 

 posing complete and instantaneous combustion. If it is desired 

 to obtain instead the total calorific effectiveness, as in heating 

 water below its boiling-point, in which case the latent heat of 

 the steam of combustion becomes also available, the above expres- 

 sion is changed by simply omitting the subtrahend in the nu- 

 merator : 



*= a oo?r a w , =3192° C. =5778° F. 

 4-3245 + 6-4714 



oversight of regarding this figure as the temperature when " the gases can 

 freely expand, as is the case in an open flame/' overlooking the correction 

 necessary in this case for the latent heat of steam of combustion, as is ex- 

 plained in the text above. 



