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



text-books for equal weights of the gases ; but we have reduced, 

 them to the standard of equal volumes also, as more suitable to 

 our present purpose. This reduction is made simply by multi- 

 plying the equivalents for weights by the densities as given in 

 the third column. 



Table I. 





Total calorific equi- 

 valents. 



Densities 

 on scale of 

 hydrogen 



Of equal 

 weights. 



Of equal 

 volumes. 





34462 C. 



2403 

 13063 

 11858 



34462 C. 



33642 

 104504 

 166012 



1 

 14 



8 

 14 



Carbonic oxide 







The meaning of this Table is simply that equal weights of 

 water would be heated by the several gases to temperatures pro- 

 portional to the numbers in the first column when equal weights 

 of the gases are burned, and proportional to those in the second 

 column when equal volumes are burned. 



A cursory glance at the figures in the second column of this 

 Table might seem to justify the notion hitherto entertained by 

 many, of the comparatively low calorific powers of hydrogen and 

 carbonic oxide ; and it was doubtless as a consequence of such a 

 comparison as this that statements have been put forth and 

 widely accepted among American gas-engineers to the effect that 

 the weight of water heated from the freezing- to the boiling- 

 point by one cubic foot of the four main components of illumi- 

 nating gas, respectively, is as follows : — 



Hydrogen 2*22 lbs. water. 



Carbonic oxide .... 2*16 „ 



Marsh-gas 6*17 „ 



Olefiant gas .... 107-i „ 



the figures here being obviously about in the same ratio as those 

 in the second column of Table I. Several most grave errors, 

 however, are here involved. To get at the true relative calorific 

 effects of the above gases when burned in the open air in heating 

 water below its boiling-point, deductions must be made, not only 

 for the specific heats of the products of combustion of the gas, but 

 also, more important still, for the specific heat of the nitrogen of 

 the air required to burn the gas. In fact, when we consider that 

 for each volume of oxygen required to burn a given volume of a 

 gas about four volumes of nitrogen must be heated up to the 

 temperature of the flame, it becomes easy to conceive, what 



