516 Proceedings of Royal Society of Edinburgh. [sess. 
From these results a first approximation to the expression for 
the equilibrium was then obtained in the same manner as for 
solutions containing potassium sulphate and sulphuric acid. The 
concentrations were first introduced into the expression deduced 
directly from the experimental results with the latter solutions, 
and from the constants thus obtained a correcting factor was 
calculated as before. 
The values of K which satisfy the expression 
(7.H 2 S0 4 (1 - of) x aNa 2 S0 4 (l - a 2 ) = K{ C.NaHS0 4 (l - as)} 1 * 15 
are as follows : — 
h 2 so 4 
A T a 2 S0 4 
K 
0*025 
f 0*1 
0*242 
0*05 
0*260 
0*1 
jj 
0*277 
02 
jj 
0*338 
0*35 
jj 
0*323 
They exhibit the same marked and almost regular increase from 
the beginning to the end of the series. 
The above expression may be written 
a.H 2 S0 4 (l - a 4 ) X ai\a 2 S0 4 (l - a 9 )_ F _ A I a.H 2 80 4 (l - cq) \y 
C.{lS r aHS0 4 (l - ag)} 1 * 15 ( C.NaHS0 4 (l - a 3 ) J 
where y, as before, is the mean value of the quantity 
A log.K 
GH,SQ 4 (1— a,) 
°'C.NaHS0 4 (l -a s ) 
and in this case is equal to 0*370. 
On simplification the expression reduces to 
{aH 2 S0 4 (l- ai )} 0 * 63 A 
{ ai S T aHS0 4 (l - a 3 )} 0 * 78 C.Na 2 S0 4 (l - a 2 ) ’ 
and in order that it may be symmetrical with that already found 
for potassium sulphate solutions, the exponent belonging to the 
sulphuric acid was made equal to 0*85, and the expression then 
becomes 
{C.H 2 SO 4 (l-a 1 )}0-“ Aj 
a.NaHS0 4 (l - a 3 ) { <7. Na 2 S0 4 (l - a 2 )p 35 
