210 
PROFESSOR TYNDALL ON THE ABSORPTION AND 
the first chamber from 2-8 inches to 15-4 inches we increase the absorption of olefiant gas 
nearly 20 per cent., the shortening of the second chamber by precisely the same amount 
effects a diminution of barely 4 per cent, of the absorption. All these results conspire to 
prove the heterogeneous character of the radiation from a source heated to about 250° C. 
The sum of the absorptions placed side by side with the absorption of the sum ex- 
hibits the influence of sifting in an instructive manner. Tables VI., VII., VIII., IX., 
and X., thus treated, give the following comparative numbers : — 
Table XI. — Carbonic Oxide. 
Length of Chambers. 
Sum of Absorptions. 
Absorption of Sum. 
2-8 
46-6 
19-7 
12-9 
8-0 
41*1 
21-8 
12-9 
12-2 
37-2 
22-9 
12-9 
15*4 
34-0 
rH 
CO 
CM 
13-4 
17-8 
31*6 
23*1 
13-3 
36'3 
13-1 
22-9 
13-4 
Means 22 • 3 
13-1 
Table XII. — Carbonic Acid. 
Length of Chambers. 
Sum of Absorptions. 
Absorption of Sum. 
2-8 
46-6 
22-4 
13-3 
8-0 
41-4 
22-6 
13-0 
12-2 
37-2 
22-4 
13-0 
15-4 
34-0 
23-9 
13-9 
23-8 
25-6 
23-1 
13-1 
36-3 
13-1 
21-6 
12-3 
Means 22-6 
13-1 
Table XIII. — Nitrous Oxide. 
Length of Chambers. 
Sum of Absorptions. 
Absorption of Sum. 
2 8 
46-6 
49*0 
33-9 
12-2 
37-2 
53-1 
32-0 
15-4 
34-0 
53-2 
32-0 
17-8 
31-6 
55-8 
32-7 
Means 52-8 
32-7 
Table XIV. — Olefiant Gas. 
Length of Chambers. 
Sum of Absorptions. 
Absorption of Sum. 
2-8 
46-6 
100-7 
67-7 
8-0 
41-4 
109-5 
67-5 
12-2 
37-2 
109-4 
65-0 
15-4 
34-0 
115-9 
67-0 
Means 108-9 
66-8 
