THERMAL EFFECTS OF FLUIDS IN MOTION. 
333 
Table XI. — Experiment in which carbonic acid was forced through a plug consist- 
ing of 740 grs. of sik. Mean barometric pressure 30 065, equivalent to 14*723 lbs. 
on the inch. Gauge under atmospheric pressure 145*65. Pump placed in con- 
nexion with the pipe immersed in carbonic acid at ll h 37 in . Per-centage of 
moisture in the carbonic acid 0*15. 
1 . 
2. 
3. 
4. 
5. 
6. 
Time of 
observa- 
tion. 
Volume per- 
centage of car- 
bonic acid. 
Pressure-gauge, and 
pressure in lbs. on the 
square inch equivalent 
thereto. 
Indication of thermometer. 
Temperature of the bath. 
Indication of thermometer. 
Temperature of the 
issuing gas. 
Cooling 
effect in 
Cent, 
degrees. 
h m 
11 28 
35-5 
318-9 
117*9 
30 
35-1 
318-95 
118-0 
32 
35-6 
318-95 
118-0 
34 
35-2 
318-95 
117-9 
36 
35-2 
318-95 
117*73 
37 
36-0 
318-95 
117-5 
38 
36-2 
318-95 
112-0 
39 
95-51 
36-6 
94-0 
43 
36-9 
319-03 
83-95 
45 
95-51 
370 
83-6 
47 
37*1 
83-0 
50 
95-517 
37-07 
319"05^ 
82-6 " 
53 
37-0 
82-4 
55 
95-51 
37-0 
lbs. 
319-15 
82-35 
57 
^95-51 
37-0 
^37-0 = 75-324 
^319*17 = 12-844 
82-3 
^82-62=7-974 
4-87 
12 0 
95-51 
37*0 
82-7 
2 
37-0 
319-3 
83-0 
5 
95-51 J 
37*0 J 
_ J 
83-0 J 
In order to ascertain the cooling effect due to pure carbonic acid, we may at 
present neglect the effect due to the small quantity of watery vapour contained by 
the gas ; and as the cooling effects observed in the various mixtures of atmospheric 
air and carbonic acid appear nearly consistent with the hypothesis that the specific 
heats of the two elastic fluids are for equal volumes equal to one another, and that 
each fluid experiences in the mixture the same absolute thermo-dynamic effect as if 
the other were removed, we may. for the present take the following estimate of the 
cooling effects due to pure carbonic acid, at the various temperatures and pressures 
employed, calculated by means of this hypothesis from the observations in which 
the per-centage of carbonic acid was the greatest, and in fact so great, that a con- 
siderable error in the correction for the common air would scarcely affect the result 
to any sensible extent. 
