338 Dr. Watts on the Temperature and Heating -powers of Flames. 



numbers 33642 and 166012. We conclude, therefore, that the 

 numbers quoted on p. 292, in which, according to Messrs. Silli- 

 man and Wurtz, " several most grave errors are involved," do, 

 in reality, strictly represent the heating-effects of the different 

 gases when employed to the greatest advantage in heating water 

 below 100° C. 



The omission of the correction for the latent heat of steam in 

 Bunsen's original calculation of the temperature of the hydrogen- 

 flame has been already pointed out by Dibbits*. 



In the calculation of the temperature of the hydrogen-flame 

 given in this paper (p. 294) there is also an error in assigning to 

 liquid water the specific heat 0*4805 instead of 1 : the formula 

 should be 



34462-9(637-48-05) 



4-3245 



6743° C. 



Another of the conclusions arrived at in this paper is erro- 

 neous, viz. "That, of all known gases, the highest calorific effectsf, 

 under ordinary atmospheric conditions, are obtainable from car- 

 bonic oxide, whose calorific value,above 100°C.,is about 3000°C." 



The flame of cyanogen is hotter than that of carbonic oxide — 

 the calculated temperature of the flame of cyanogen in air being- 

 SSI^ C, and in oxygen no less than 10557° C. It must be 

 remembered, however, that these results of calculation in no way 

 express the actual flame-temperatures. The calculated tempera- 

 ture of the oxyhydrogen-flame is 6743° C. ; but the experiments 

 of Devillej and Bunsen§ agree in fixing between 2500° C. and 

 2800° C. The following are the calculated and experimental 

 flame-temperatures of certain gases. It will be seen that the 

 flame of cyanogen is shown by experiment also to have the high- 

 est temperature : — 



( 



Calculated. 



Experimental. 



Hydrogen in air . . 



2701 C. 



2024 C. 



Hydrogen in oxygen 



6743 



2844 



Carbonic oxide in air 



2996 



1997 



Carbonic oxide in oxygen. 



7067 



3033 



Cyanogen in air . 



3519 



3297 



Cyanogen in oxygen . 



10557 





defiant gas in air 



2727 





Olefiant gas in oxygen . 



8606 





* Pogg. Ann. vol. cxxii. p. 49/. 

 t Read "flame-temperatures." 

 X Legons sur la Dissociation, p. 281, 

 § Pogg. Ann. vol. cxxxi. p. 161. 



