362 REPORT—1905. 
is indicated on the diagram by marking with a cross the molecule which is exactly 
halfway through the partition. 
At B a single solute molecule, s, has been introduced at the right side. If this 
molecule exactly cancels the energy of one solute molecule at its own end of the 
row, the equilibrium point will move one molecule to the right, the solvent mole- 
cules will move in the same direction, and one of their number will enter on the 
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solution side. So long as the row includes one, and only one, solute molecule, the 
equilibrium will remain unchanged and no more solute molecules will pass in. If 
another solute molecule arrives on the scene, the equilibrium will again be disturbed 
in the same way as before, and another sulvent molecule will pass into the solution. 
This mechanism accomplishes to some extent the work of a ‘Maxwell Demon,’ 
in so far at least as it takes advantage of the movement of zxdividual molecules to 
raise one part of a system at a uniform temperature to a higher Jevel of energy. 
A Mechanical View of Dissociation in Dilute Solutions. 
The view that the phenomena of solution depend on the relative kinetic energy 
of the solvent and solute molecules appears to apply with special force to the phe- 
nomena of dissociation in dilute solutions. Under the gas theory there does not 
appear to be any reason why the solute molecules should dissociate into their ions. 
So obvious is this absence of any physical motive that Professor Armstrong has 
happily referred to the dissociation as ‘ the suicide of the molecules.’ Others have 
proposed to ascribe the phenomenon to what might be called ‘ the fickleness of the 
ions,’ thus supposing that the ions have an inherent love of changing partners, 
These may be picturesqne ways of labelling certain views of the situation, but the 
views themselves do not appear to supply any clue to the physical nature of the 
phenomena. With the acceptance of the view that the phenomena of solution are 
largely due to the kinetic energy of the solvent molecules, the phenomena of dis- 
sociation also appear to take their place as a natural result of this activity. For 
consider the situation of an isolated molecule of cyanide of gold and potassium 
closely surrounded by and at the merey of some millions of water molecules all 
in a state of intense activity. The rude mechanical jostling to which the complex 
molecule is subjected will naturally tend to break it up into simpler portions 
which are mechanically more stable. The mechanical analogy of a ball mill in 
which the balls are self-driven at an enormous velocity is probably rather crude, 
but it may at least help us to picture what, on the view now advanced, must be 
essentially a mechanical operation, 
