i. 
| and the Properties of Substances. 179 
Brace, however, it is undoubtedly enormously higher, it follows 
that copper in the solid and molten state consists in practice of 
| molecules having the formula Cn,, where 7 is probably quite large. 
‘The same conclusions can be arrived at in respect to all the other 
metals, and a large number of chemical compounds such as the 
various salts etc. 
It will be apparent from equation (2) that the value of 7, 
increases with that of =, c,, Lherefore the partial polymerization 
of a liquid should have the effect of raising its critical temperature. 
An important case in point is water, whose critical temperature 
would be 159:5°C. instead of 631°C., if the chemical formula for 
each molecule were H,O. If each molecule were polymerized to 
the same extent its chemical formula would be 7°8 (H.O). It 
appears, however, from surface tension considerations that water 
consists of molecules polymerized to different extents. The mole- 
cular weight of some of the molecules must thus be greater than 
that according to the above formula. It may be pointed out here 
that the determination of the extent of polymerization of a liquid 
from Oetvos’ surface tension equation cannot lead to very accurate 
results since it is tacitly assumed that the critical temperature is 
not influenced by polymerization. 
: Another interesting case in this connexion is the molecular 
Weight of liquid mercury. If we take cy, and c, equal to »/m,, 
| which we have seen is approximately the case, we obtain 604°9° C. 
} 
| 
for the critical temperature. But it is undoubtedly much higher, 
from which it follows that mercury must be partially polymerized. 
This we have shown to be the case by a different method in a 
previous paper*. 
' * Proc. Camb. Phil. Soc., vol. xvii. p. 157. 
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