PROFESSOR TYNDALL’S CONTRIBUTIONS TO MOLECULAR PHYSICS. 357 
Four months subsequent to the performance of the above experiments, a second series 
were made with olefiant gas, and the following results obtained : — 
Table XXXIII. 
Radiation through dry Olefiant Gas. Source, small carbonic-oxide flame. 
Tension in inches. 
Deflection. 
Absorption. 
From Table XXXI. 
1-0 
ii-4 
23-2 
48-0 
2-0 
17*0 
34-7 
55-5 
3’0 
21-6 
44-0 
60-3 
4-0 
24-8 
50-6 
65-1 
5-0 
27-0 
55-1 
68-6 
10-0 
32-1 
65-5 
74-3 
Beside the absorption by olefiant gas, I have placed that by carbonic acid derived 
from Table XXXI. The superior power of the acid is most decided in the smaller 
tensions ; at "a tension of an inch it is twice that of the olefiant gas. The substances 
approach each other more closely as the quantity of gas augments. Here, in fact, both 
of them approach perfect opacity ; and as they draw near to this common limit, their 
absorptions, as a matter of course, approximate. 
The temperature of a hydrogen-flame, as calculated by Bunsen, is 3259° C., while that 
of a carbonic-oxide flame is 3042° C. The foregoing experiments demonstrate that 
accord subsists between the oscillating periods of these sources and the periods of 
aqueous vapour and carbonic acid at a temperature of 15° C. The heat of the flame 
goes to augment the amplitude, and not to quicken the vibration. 
Sent through carbonic oxide, 
following absorptions : — 
the radiation from the carbonic-oxide flame 
Table XXXIV. 
Radiation through Carbonic Oxide. Source, 
carbonic-oxide flame. 
Tension in inches. 
Deflection. 
Absorption. 
1 
18-0 
29-0 
2 
27-0 
43-5 
4 
34-0 
56-4 
10 
37-3 
65-5 
The absorptive energy is here high — greater, indeed, than that of olefiant gas ; it 
falls considerably short, however, of that exhibited by carbonic acid. This result shows 
us that the main radiant in the flame is its product of combustion, and not the carbonic 
oxide heated prior to combustion. 
Wishing to examine the radiation from a flame whose product of combustion is 
sulphurous acid, through sulphurous acid, I resorted to the flame of bisulphide of carbon. 
