1 A- 1 1 



2a [/p^ ,y » 2a k 



s' 



(see above), hence if — .r/ = a-/ =z /('Xj'. 



a^ — s'^ 



2a' 



Multiplying by the factor io X , we liave therefore for the 



s{a^ — s") 



first part of a : 



a» 1 1 l/ï^^ 



^>=^X ,, BgUg--=o>X—, ^BgUg . . (10) 



s [a* — s') k n (1 — n^) n 



Hence we find for this a vakie which no longer contains ({ (hence T), 

 so that the part of the constant of attraction which i-efers to the 

 passing molecules, appears to be independent of the temperature. 

 This seems somewhat strange, because near the hmiting temperature, 

 given by (p^, 6^ gets near 90^, so that then the limits of /, with 

 respect to get nearer and nearer to each other, and (inally coincide 

 at <^j rrr 9(P ((f = ff ^). It woiild therefore be expected tliat aj would 

 become smaller and smaller according as T decreases, and that it 

 would disappear at the limiting temperature. However, this is not 

 the case according to (10). The explanation may be found by an 

 examination of the paths of the molecules, which shows that with 

 the diminution of the velocity ?/„ they occnpy an ever larger portion 

 of the path within the sphere of attraction ; to which the circumstance 

 is added that the frequency for the angle, which is proportional to 

 sinO, reaches its niaximuni exactly in the neighbourhood of (^ = 90°. 



When n is near i, i. e. a near s (very thin sphere of attraction), 



1— «^ 

 Bq'^tq approaches , so that then ai approaches «j : n' = oj. As 



"^ "■ n^ 



sinV), is = "- (1 + r/), mvV;„ = .r„^ = 1 — "^ (1 + y), so that ..;-' will 

 a « 



a' - s' 

 lie between =1 — )f^±0 at high temperatures (r^ = 0), and 



a^ 



(0) at lower temperatures {<p = ffj. 0^ lies, therefore, in both cases 

 in the neighbonrhood of 90°, hence the limits of integration of 7i 

 will almost coincide, viz. between ± 90° and 90° at high temperatures, 

 I'esp. (90°) and 90° at lower temperatures. 



In the case n-^\ the limiting value (f^-=.{\ — n''):n^ will lie near 

 0, i.e. T^ near oo, so that the available range of temperature is 

 exceedingly small. 



If, however, n is near 0, i.e. a very much larger than s (very 



