( 619 ) 



particles, and hence be acquainted with the structure of the particles 

 (cf. § 1), in which also the origin (cf. Comm. N". 'J 04", § 4) 

 would come in for discussion. However, it is to be expected that 

 when the particles are small compared with the wavelength of the 

 light, the intensity of the scattered light will increase proportional 

 to the square of the quantity of condensed substance, whereas when 

 the particles are no longer so small, the increase will take place 

 more slowly. 



To whatever cause we mtiy attribute the occurrence of the diffe- 

 rences in density, the great compressibility of the subsi^ance in the 

 neighbourhood of the critical state will have a preponderating in- 

 fluence on it. Thus e.g. the mean deviation in density governed by 

 the statistic equilibrium (Smoluchowski) ') will be proportional to 

 y'dp/dg {q = density). If we assume that the substance condenses 

 round centres of attraction which exert forces on the surrounding 

 particles of the substance which per unit of mass are only dependent 

 on the distance, the quantity which is condensed round every cen- 

 trum of attraction is proportional to ^) djj/do. 



In order to examine what information the data in table III give 

 on a connection between the inlensity of the scattered light and the 

 compressibility, we notice that in the neighbourhood of the critical 

 point dp/dQ = q^^(T — 7\), if the average density of the substance 

 differs so little from qi^ that the following term ^q^^ (9 — o/^y may 

 be neglected (so T — Tk not too small). 



TABLE V. 



1) M. V. Smoluchowski, Ann. d. Phy.s. (4; 25 1908 p. 205. 

 *) In this it is supposed that the condensation is so insignificant that f in a 

 condensed part remains sufficiently near /* , 



