1917-18.] 
Thermodynamics of Adsorption. 
35 
a 
_ _ YT 
A * 
dp' 
0T/a 
3A\ Cl rj-\ 
da) t A 
( d P_\ 
' \3TA 
3A\ 
3P 
/* 
dp' 
dajy 
= ® y t 
A ' \3T/] 
dp 
da 
Now 
= RT 2 . . 
A\3T/r \31oga/T 
Aoc -y a l oc v 0 : s approx. 
1 0A_2 
” AST" 5 a 
where a is the coefficient of volume expansion of the adsorbent, 
0 log p 
d log a 
= n 
where n is usually greater than unity, but finite. 
Hence, assuming the adsorbing carbon to have the coefficient of expan- 
sion of graphite (and not of a liquid), 
_ . YT . 
A 
dp 
/d A) =? x -000024 x«RT 2 
v0T/a \daj t 3 
= ’005RT n 
= ’00012 n per c.cm., 
which is negligible compared with the terms to be corrected. 
Again, we have 
- °o = - 
p aV 
A 
dp 
o 
- RT f ~ — approx. 
Jo A p 
da — 
07 
0T 
■ydcr — 
= -r[ p — ^_rt 
Jo A p 
f p / 1 0a a 0A \dp 
lo \AdT~A 2 dfJj 
<T - <T n — T 
0 0T 
Now 
<r 0 -D m2p/l 3a a 0A\<ip 
Jo {AdT~AJdT)J’ 
-prno f p a 3A dp -orpo f p 2 a dp 
KJA -77: = — = RT 2 / _ - a . — . — approx . 
Jo A 2 3T» Jo 3 A p 
p Jo 6 A P 
where a is the coefficient of volume expansion 
= - ?aRT 2 P— ^ 
3 Jo A p 
= ~ ~ ^o) 
= ’0044(cr - cr 0 ), 
which is negligible compared with (cr — cr 0 ). 
