( 620 ) 



In tabic V the data of table III have i>ocn compared with the 



5 



formula: int^^ — (//, = 1J°.18, see p. (315). 



T— 2 k 



The curve in PI. II fig. 2 represents Iok' 



The differences — C are of two kinds : 



1. The deviation at 11°. 24 : this was to be expected in the 

 immediate neighbourhood of the critical temperature, as the formula 

 for Tk would give an infinite intensity; here the infiuence makes 

 itself felt of following terms in the development of ö/:*/f)o, or of the 

 intensity of the scattered light as function of the quantity of sub- 

 stance (see p. 619); 



2. also at tempei-atures further from the critical temperature 

 there is a systematic de^4ation : the observed curve of intensity 

 ascends here more rapidly than the calculated one. This might among 

 others be m connection with the observation of Tkavkrs and Usher ^), 

 who found that the maximum of the intensity of the opalescence 

 should not lie at 71-, but for SO, 0°.05 above Tk. 



Leaving these deviations out of account we may conclude that 



on the main the observations conform to the mentioned equation. 



0.25 



The deviations from a formula lot = — would have been 



{T—fkY 



much larger. The correction mentioned in the beginning of this 



§ will not affect this conclusion. 



On the supposition that at least when the dimensions of the 

 volume elements in which appreciable condensations or rarefactions 

 are found, are small with respect to the wavelength, the intensity 

 of the scattered light is proportional to the square of the quantity 

 of substance which has condensed round every centrum, or to the 

 square of the mean deviation in density governed by the statistic 

 equilibrium, it follows that our observations rather support the 

 hypothesis of the condensations and the rarefactions caused by the 

 molecular movement and governed by the statistic equilibrium, than 

 the hypothesis of centres of atti'action whose number remains constant 

 with varying temperature. 



If it appears from further investigations that the absolute value of 

 the intensity of the light scattered by the mist is in harmony 

 with what is to be expected according to the distribution law of 

 BoLTZMANN (cf. Smoluchowski, loc. cit.) a connection may be formed 

 between the observations of the intensity of the light scattered by 

 the mist and the disturbance function in the equation of state in 



1) M. W. Travers and F. L. Usher. Proc. Roy. Soc. A. 78 (1906;, p. 247. 



