16 
PEOl’ESSOE TYNDALL ON THE ABSOEPTION AND 
entering the tube the vapour had only the tension due to the temperature of the labo- 
ratory, namely 12 inches. This would require to be multiplied by 2‘5 to bring it up to 
that of the atmosphere. Hence the TWoth of ^ cubic inch, the absorption of which 
I have affirmed to be capable of measurement, would, on being diffused through a tube 
possessing a capacity of 220 cubic inches, have a tension of X ^Xtwo = TooVoo^h 
part of an atmosphere ! 
I have now to record the results obtained with thirteen other vapours. The method 
of experiment was in all cases the same as that just employed in the case of ether, the 
only variable clement being the size of the unit-measure ; for with many substances no 
sensible effect could be obtained with a unit volume so small as that used in the expe- 
riments last recorded. With bisulphide of carbon, for example, it was necessary to 
augment the unit-measure 50 times, to render the measurements satisfactory. 
Table VI. — Bisulphide of Carbon. 
Unit-measure ^ a cubic inch. 
Absorption. 
A 
Measures. 
observed. 
Calculated. 
1 
2-2 
2-2 
2 
4-9 
4-4 
3 
6-5 
6-6 
4 
8-8 
8-8 
5 
10-7 
11-0 
6 
12-5 
13-0 
7 
13-8 
15-4 
8 
14-5 
17-6 
9 
150 
19-0 
10 
15-6 
22-0 
11 
16-2 
24-2 
12 
16-8 
26-4 
13 
17-5 
28-6 
14 
18-2 
30-8 
15 
19-0 
33-0 
16 
20-0 
35-2 
17 
20-0 
37-4 
18 
20-2 
39-6 
19 
21-0 
41-8 
20 
21-0 
44-0 
As far as the sixth measure 
the absorption is 
proportional to the dei 
the effect of each successive measure diminishes. Comparing the absorption effected by 
a quantity of vapour which depressed the mercury column half an inch, with that 
