368 
On the Measure of Temperature, 
[Dec. 
1. Carbonic Acids, 
Excess of temp, 
of the therm, 
over that of the 
gas. 
Rates of cooling due solely to the contact of the gas. 
Pressure 
0m,72. 
Pressure 
0®,36. 
Pressure 
0m,18. 
Pressure 
0 m ,09. 
Pressure 
200° 
5°, 25 
3°, 64 
2°, 5 6 
1°,79 
1°,25 
180 
4 ,57 
3 ,22 
2 ,25 
1 ,56 
1 ,09 
160 
4 ,04 
2 ,80 
1 ,97 
1 ,37 
0 ,95 
140 
3 ,39 
2 ,38 
1 ,65 
1 .17 
0 ,80 
120 
2 ,82 
1 ,97 
1 ,36 
0 ,95 
0 ,67 
100 
2 ,22 
l ,55 
1 ,08 
0 ,76 
0 ,52 
80 
1 ,69 
1 ,17 
0 ,82 
0 ,57 
0 ,40 
60 
1 ,18 
0 .82 
0 .57 
0 ,40 
0 ,28 
2. Olefiant Gas. 
Excess of temp, 
of the therm. 
over thatef the 
gas. 
Rates of cooling due solely to the contact of the gas. 
Pressure 
U ra ,72. 
Pressure 
0m, 36. 
Pressure 
0 n ', 18. 
Pressure 
0m,09. 
Pressure 
0 m ,045. 
200° 
7 ,41 
5°, 18 
3°, 44 
2°. 58 
1°,84 
180 
6 ,45 
4 ,57 
3 ,17 
2 ,22 
1 ,59 
160 
5 ,41 
3 ,86 
2 ,72 
1 ,89 
1 ,34 
140 
4 ,70 
3 ,31 
2 ,35 
1 ,63 
1 ,U 
120 
3 ,84 
2 ,76 
1 ,92 
1 ,35 - 
0 ,96 
100 
3 ,12 
2 ,21 
1 ,55 
1 ,08 
0 ,78 
80 
2 ,34 
1 ,62 
1 ,15 
0,79 
0 ,62 
Mean valve of all the ratios : 
For carbonic acid gas, 1,431. 
For olefiant gas, 1,415. 
” e may now, then, from all that precedes, draw the following conclusions 
Imo. The rate of cooling due to the sole contact of a gas increases as a certain 
function of the difference of temperature, whatever the elasticity of the gas. 
2 do. For the same difference of temperature the cooling power of a gas varies 
in geometrical progression when the tension varies in geometrical progression; 
and if we suppose the ratio of the second progression to be 2, then the ratio of 
the 1st will be 1,366 for air ; 1,301 for hydrogen ; 1,431 for carbonic acid , and 
1,415 for olefiant gas. 
This result may be exhibited in another and more simple form, by the aid of the 
following transformations: 
Let /' represent the cooling power of the air, haring its tension = p. This 
power will become P (1,366), with a tension p 2; P (1,366)* with a tension p 2* ; 
and finally with a tension p 2° it will be P (l,366) n . Now putting p 2 a zz. p aad 
P (l,366)n — p' 
we shall have, by eliminating n : 
Log. P' — ■ log. P Log. pf — . log. p 
Log. (1, 366) Log. 2 
whence, returning to numbers, 
In the same way for hydrogen we shall find 
for carbonic acid the exponent will be 0,517, and for olefiant gas 0,501. 
