276 
And between O° and 1000° C.: 
13,5956 —11,1248 1700 
oy= Sf ee 
1000 4,15 
hence y = 0,506 = 0,51, almost equal to the value between 0° and 
300° C. The value y=0,5 is that which is due to “ideal” sub- 
stances with a and 6 invariable (chiefly 6 no function of v). We 
saw above that below 1000°C. also the value of f (viz. 4,1) points 
to the quasi-ideal behaviour of mercury at those comparatively lower 
temperatures. 
7. General Formulae for v,, T., p,. and s. 
When wv, is the critical volume (expressed in normal units) of 
1 Gr. atom, then. 
__ 200,64 
rt Aen 
hence with D= 4,15: 
200,64 
ve = rbe = — (002157 ~~ ae (1) 
AAT eN 
Accordingly the value cf 6. with given D, will only depend on 
yr. If e.g. r= 2, then 5, would be —= 108.105, but if r should be 
=— 1,8, 6. would become = 120.105. 
8 a! 
For 7, holds the relation RT, = X0, hence 
Ve 
: 
RT) a oe ee Ee 
Ales 
in which a, and 6, refer to 1 Gr. atom (200,6 Gr. mercury), so 
that in reality a', =n?a, and b'.=n6,, when n = 2: (1 +2) repre- 
sents the factor of association *). 
In normal cases (n—=1 or 2) @ is a factor somewhat smaller 
than unity, which we before represented by 2. (If e.g, r= 2, we 
find for 2 the value *7/,,, whilst for ideal substances (r = 3) 4 
becomes = 1). 
1) From 1 single molecule (or atom) = !/, double molecule */3 (1—a) + '/. (22) = 
ly (1 ++) molecules arise on dissociation of the double molecule. These molecules 
occupy the molecular volume b, (leaving contraction out of account; this has been 
reckoned with in the factor 6), so that every molecule on an average occupies thé 
volume 0b’. = be: '/, (1 + x) =b-*X2:(1 +2). If the degree of dissociation x of 
the double molecules = 0, then n = 2: (1 + x) = 2, hence bc = 2b, (all the molecules 
are then double molecules). And when «= 1 (all the molecules single), then” = 1 
and b’, = be. And the same thing holds with regard to Va and v. 
