16 
MR. J. W. CAPSTICK OH THE RATIO OP THE SPECIFIC HEATS 
I. 
II. 
Gras taken. 
100-61 
98-8.5 
After adding oxygen. 
369-43 
461-83 
After explosion. 
171-49 
268-23 
After absorption of the CO 3 -w'ith potash 
72-06 
171-80 
The first gives as half the contraction 98'97, and the CO 3 formed 99‘43, their ratio 
being '9954. 
The second gives 96'80 for the half-contraction, and 96’43 for the COg, their ratio 
being 1'003. 
These ratios should be unity for pure methane. 
The difference between half the contraction and the volume of gas taken, and between 
the CO 3 formed and the original gas, gives two estimates of the air from each analysis. 
These are 1‘64 and 1'18 from the first, and 2'05 and 2*42 from the second. The 
discordance of these is wider than was usually obtained. An error of millims. in 
reading the level of the mercury when measuring the volume of the gas taken would 
account for the difference. The measuring tube of the Dittmar gas analysis apparatus 
was rather too narrow, as the shape of the meniscus varied with the state of the 
surface of the mercury. 
The mean of the four gives 1*88 per cent, for the air. 
The S.G. of the gas is got from the equation 
which gives 
lOOp = 1-88 -f 98-12 X -5528, 
p = -5612. 
Two sets of measurements of the methane figures gave as tlie half wave-lengths 
63-126 millims. and 63-130 millims., and the length of the air figures was 48-880 millims., 
the temperature being 19-2°. 
Hence, the ratio of the specific heats of the mixed gases is 
63-128\3 
48-880y 
= 1-316. 
1-408 X -5612 X 
Finally, from the equation 
p/(r - 1 ) =pj{y, - 1 ) +P 3 /(y 3 - 1 ), 
100/-316 = 1-88/-408 + 98-12/(y - l), 
y = 1-314. 
we have 
which gives 
