OF THE FLATTIE IN THE EXPLOSION OF GASES. 
329 
combines more slowly to lorm carbonic acid. How far this second reaction is 
completed when the reflexion-wave is measured it is impossible to decide. On the 
assumption that the sj^ecific heat of nitrogen is constant and that of COo is 7‘2, the 
velocity of the wave in the completely burnt mixture would indicate a temperature 
of 4200° C. ; on the assumption that the specific heats of COo and Nj are 20 and 7, 
the temperature indicated is 4780° C. On the other hand, if no carbonic acid had 
yet been formed, the temjoei'ature indicated for the mixture of diatomic gases 
(200, On, No) is 2880° (C„ = 4-8). 
In a similar manner, the temperatures corresponding to the velocity of the reflexion- 
waves have been calculated for the other mixtures, (1) assuming the ratio of the 
specific heats for a diatomic gas to be 1'41 and for a triatomic gas 'i"28, and 
(2) assuming the ratio of the specific heats for a diatomic gas to be 1‘29 and for a 
triatomic gas I'll. 
Table III. — Temperatures of Exploded Gases, Calculated from the Velocities of 
the Reflexion-Waves. 
Mixture. 
j f 7 for diatomic gases = 1 ’41. 
\ 7 for triatomic gases = 1 • 28. 
II -f gases = 1 • 29. 
\ 7 for triatomic gases = 1 • 11 
2Ho + 0., 
°G. 
3720 
° C. 
48.30 
Ho + NoO 
3660 
4130 
2C6 + Oo 
4530 
5250 
CoN, + Go 
3330 
3670 
CoNo + 20o 
4200 
4780 
2CoHo + 50o 
3980 
4630 
A glance at this table reveals the fact that, whether the specific heats vary or not, 
but on the assumption that combustion is complete in each case, the explosion ot 
cyanogen to carbonic oxide (which according to all observers gives the l^rightest flash 
and the highest pressure) gives apparently the coolest comljustion products a short 
time after the explosion-wave has gone by. Now I have found'^'' that the velocity or 
the reflexion-wave is nearly equal to that of a true sound-wave of small displacement 
travelling through the flame j^roduced by the explosion of cyanogen burning to 
carbonic oxide; it is not tlierefore open to us to reject the temperature calculated for 
this mixture as entirely wide of the truth. The natural inference to be drawn from 
the figures is, I tliink, that the combustion is not complete in the other mixtures (in 
all of which steam or carbonic acid, or both, are produced) at the moment the reflexion- 
wave is measured. If we suppose that the formation of carbonic acid and steam is 
incomplete, the densities of the products are less and y is higher, and consequently 
the temperatures calculated from the velocities of the reflexion-wave would be 
lowered. For instance, if we assume in these several experiments that the hydrogen 
* See Part III. 
2 U 
VOL. GC.—A. 
