﻿648 Prof. Porter and Mr. Hedges on the Law of 



theory, this cannot be taken as indicating more than that in 

 the differential equation for the distribution there is a term 

 proportional to n 2 in addition to the one depending on n. 



Fis. 2. 



10x10 

 9 

 8 



,3 5 



$ 4 



^ « — 2' — ' 3- 



' S^ 



^ 



_L Z ± 





1- -J- 



L / 



I 1 



4 



f 



J- 7 -P 



j- i- 



T 7 -C 



r r 



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-M- 



/2*\ 



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01 -02 03 -04 -05 -06 07 -08 -09 10 II -!2 -13 14 -15 

 Depth in Centimetres. 



Perfect Gas Law O O Burton's Equation 



-J — J — f- Experiment ai Points — • •— Porter and Hedges 



From the form which Burton gives to his force term there 

 appears to be some confusion in his mind between force 

 and pressure. If his statements were to be taken as correct, 

 there would be a uniform force on any layer (counteracting 

 the uniform force of gravity) in the greater part of the 

 solution, for his force term is proportional to n 2 and n becomes 

 practically uniform ; whereas it is clear that in the middle 

 where a layer would be driven as much up as down the 

 force would really vanish. 



Now, although b in a van der Waals' formula represents 

 the volume of a particle when it is treated as a rigid body, it 

 is in general the coefficient of the internal virial arising from 

 molecular repulsions during " collisions." The large value 

 obtained with gamboge would indicate therefore that, even 

 when particles are at a distance from one another much 

 greater than that which denotes their size when it is estimated 

 by optical examination with a microscope, the particles begin 

 to experience a mutual repulsion. To put it in other words, 

 the actual visible particle is connected in a semi-rigid way 

 with a very large quantity of the surrounding fluid. What 

 the nature of this connexion may be can only be a matter 



