38 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Table V. 
a . 
A. 
RT 2 [ ad]ogp da. 
Jo 0T 
ART 2 f aldlogp da 
J 0 A 0T aa ' 
AS. 
1 0A 
A 0a' 
(a) Ammonia. 
126 
(0-113) 
40-4 
44-3 
-6-4 
0-0022 
100 
•062 
33 T 
36-0 
-6-2 
•0015 
82 
• • • 
... 
. . • 
-6-0 
•0014 
63 
•040 
21-9 
235 
-5-8 
•0013 
40 
•041 
14-4 
15-6 
-5-6 
•0019 
16 
•048 
63 
6-7 
-5-3 
•004 
(b) Carbon Dioxide. 
16 
•023 
5-0 
(-5-3) 
•0022 
10 
•020 
3-0 
... 
(-5-2) 
•0024 
(c) Nitrogen. 
10 
(•05) 
2-1 
... 
(-5-2) 
•007 
1 
(■06) 
0-2 
(-4*8) 
•012 
Since A2 refers to the adsorbent in vacuo , it is independent of the 
substance adsorbed, and we can therefore place approximate values for it 
evaluate i ~ • It 
A da 
fortuitous selection of results has led to a negative value as above of the 
surface energy of the adsorbent in vacuo , namely, — 5 calories per grm. ; 
though such a negative value is not surprising. Thus a gelatine gel and 
rubber both become warmer when stretched ; * that is, in these cases also, 
2 is negative, provided their surface tension is negative.*)- It follows from 
the above negative value that adsorption is accompanied by an increase in 
surface, which is apparently most marked initially and presumably vanishes 
finally. This is analogous with the expansion of a gel on picking up 
water * and the swelling of rubber on adsorbing organic vapours. In both 
cases there is very probably an expansion of '‘surface.” 
is possible that a 
as in Table V ( b ) and (c), and thus 
Summary. 
1. The adsorption of a gas has been investigated thermodynamically 
with special reference to the heat effects accompanying adsorption. 
* Taylor, Chemistry of Colloids , p. 142. 
f Cf. Donnan’s negative surface tension of colloids. 
