346 PROFESSOR TYNDALL’S CONTRIBUTIONS TO MOLECULAR PHYSICS. 
With the same spiral, brought still nearer to its point of fusion, the following results 
were obtained with four of the vapours : — 
Table XIY. — Radiation through Vapours. Source, platinum spiral at an intense white 
heat. 
Name of vapour. 
Deflection. 
Absorption. 
Bisulphide of Carbon . 
. . 14*5 • 
2-51 
Bisulphide of Carbon . 
. . 14-5 
2-5) 
Chloroform .... 
. . 23*0 . 
' 3-9) 
Chloroform .... 
. . 23-0 
3 s * 91* 
Formic Ether 
. . 60*4 
21*3) 
Formic Ether . . . 
. . 60*5 
21-3) 
Sulphuric Ether . . 
. . 62*3 
23-6) 
Sulphuric Ether 
. . 62*5 
23-8) 
Total heat .... 
. . 82*7 
100*0 
In the experiments recorded in the foregoing Table, a total heat of 82°*7, or 588 
units, was employed ; and to test whether the absorption calculated from this high total 
agreed with the absorptions calculated from a low total, a portion of the current was 
diverted, the branch passing through the galvanometer producing a deflection of 49 0, 4. 
This corresponds to 77 units. The source, it will be observed, is here quite unchanged ; 
the rays are of the same quality, and pass through the tube in the same quantity as 
before ; but in the one case the absorption is calculated from the deflection among the 
high degrees, and in the other case it is calculated from deflections among the low 
degrees of the galvanometer. 
The experiments were limited to formic and sulphuric ether, with the following 
results : — 
Deflection. Absorption. Absorption from Table XIY. 
Formic Ether . . 17*7 
Sulphuric Ether . . 19 T 
23 21*3 
24-8 23-7 
The agreement is such as to prove that no material error can have crept into the cali- 
bration. 
Placing the results obtained with the respective sources side by side, the influence of 
temperature on the transmission comes out in a very decided manner. 
