1901 - 2 .] Mr J. Fraser on Constitution of Matter and Ether. 63 
pending on the inequality of size existing between the oxygen 
nucleus and the hydrogen atoms, and their arrangement. Fig. 2 is 
a rough attempt to give my idea of the arrangement in plan of the 
molecules of a piece of ice. This would also give the germ of the 
^explanation of the cause of water and some other bodies expanding 
on solidifying. The molecules simply arranging themselves, by 
the inequalities of pressure mentioned above, in such a way as to 
bake up more space than when in the liquid condition. 
Atomic Volumes and Isomorphism. 
It is assumed, on apparently good grounds, that the atoms of 
isomorphous bodies are of the same size. It cannot be disputed, 
of course, that they occupy the same space in the solid form , 
but this is not quite the same as saying that they are equal in 
size. Silver and gold are isomorphous bodies, as their atomic 
weights and specific gravities prove — the same difference existing 
between their atomic weights and their specific gravities, so that 
they must occupy the same space in the solid form. How, I 
think it would be a very curious fact — for there are great numbers 
of these bodies — if each set were exactly equal in size with their 
atomic weights so various, but I think the fact of their occupying 
the same space in the solid form can be accounted for in another 
way than by assuming their equality of size. It can be accounted 
for by assuming that the velocity of the particles of which the 
