THEORY OF VISCOSITY AND THERMAL CONDUCTION, IN A MONATOMIC GAS. 333 
Rigid Elastic Attracting Spherical Molecules. 
§ 10 (C) Considering next the case of rigid elastic spherical molecules which exert 
attractive forces, as in § 9 (E), we shall neglect the effect of the attractions in 
producing deflections without actual collisions, and, as in § 10 (B), we shall content 
ourselves with a second approximation to 2/3 r and 2y r . The difference between this 
case and that of rigid elastic spheres without attraction is small. The expressions 
for V (S rs b rs ) V (S rs c rs ), as far as regards the first four elements, are as follows :— 
(228) 
V (3„b„) = 
i 
14 
1 + S/T 
i 
1 4 
4 5 
TITS 
1-S/T1 
1 + S/TJ 
1+-IS/T) 
1+S/T j 
^ ( h/V r-s' 
) = 
LlI 
14 
1 + S/TJ 
, 1 -S/T 
1+ l+S/T 
20 r> i+msm 
588 1 + S/T J 
When S = 0, i.e., when there is no attraction, these reduce to (221), (223). 
The second approximations to 2/3,. and 2y r are hence found to be as follows 
2 A-= 
45 (l +fS/T) ■ 
45 (1 +fS/T)—(l—S/T) 2 (1+S/T)- 1 ’ appi ° Ximate y ’ 
- 205(l+Mt.S/T )- approximately. 
(229) 
(230) 2y,. - 205 ( 1+ i^|S/ T )-3( 1 -S/ T ) 8 ( 1 +S/T) 
Since S/T is never negative, it is clear from (229), (230) that the second approxi¬ 
mations to 2/3 r and 2y r are never less than unity. Their values, without any 
estimated correction for the error of approximation, are given in the following table, 
for various values of S/T. The correction as estimated is appended as a suffix, and 
is to be added to the last digit of the corresponding number. 
Table VI.—Rigid Elastic Attracting Spherical Molecules. 
Low temperatures. 
Moderate temperatures. 
High temperatures. 
s 
T ‘ 
00. 
5. 
' 
4. * 3. 
2. 
1. 
0-7. 0-4. 
0-2. 
o-l. j 0. ; 
CD 
2/3 r 
0 
1-038 
1 * 015 2 
1• 012 2 l-008i 
1 • 004 0 
1 
, 
l-001o 1 ’ 005 j 
1-Olio 
1-016.2 l-023 s 
CO 
2y r - 
0 
1-016 
1-009! 
1-007i l-005i 
1 • 002 0 
1 
1-OOIq 1 " 004 0 
l-009i 
1-013i 1■ 015i 
OO CD 
S a =S/3 r /2y,. 
0 0 
1-022 
1-000! 
l-005i 1• 003 0 
1 ‘ 002 0 . 
1 
1-OOOq i-ooii 
l-002i 
l-003i l-008o 
