507 
1898 - 99 .] Sulphuric Acid and Sulphates in Solution. 
separately, being rather more than 5 per cent. On the whole, how- 
ever, the constancy of K is not very satisfactory, the different values 
obtained exhibiting a marked rise with the increase in the amount 
of free acid present. This may be seen by comparison with the 
tables on p. 508. It is evident, therefore, that the formula is not 
the best which it is possible to obtain from the experimental 
results, and that by finding an appropriate correcting factor a better 
expression could be arrived at. 
Choosing two of the variable quantities, namely, the free acid 
and the acid sulphate (the value of the third variable being 
determined by these), the ratio ~ ai \ was calculated. 
C.K.Hb0 4 (l — a 3 ) 
The change in the value of the constant K corresponding to the 
change in the above ratio was then found and a new exponent y 
was thus obtained which is the mean value of the formula 
A log. K 
o, aKHS0 4 (l-a 3 ). 
The expression for the equilibrium may then be written 
C.H 2 S0 4 (1 - cq) X C.K 2 S0 4 (1 - a 2 ) _tt _ a / C.H 2 S0 4 (1 - cq ) \y 
0{.K H80 4 (l - a 3 )}!- 15 I C.KHS0 4 (1 - a 3 ) J 
where A is a new constant and y a new exponent obtained as 
above indicated. From each series four values of y can be found, 
and, assigning to each its own “ weight,” a mean value of y for 
each series is obtained, namely, 0T95, 0T28, 0T38. The mean 
of these is 0T54, and the expression reduces to 
{C.H 2 S0 4 (1 -cq )} 0 ' 85 X C.K 2 S0 4 (1 -a 2 ) _ 
C.KHS0 4 (l-a 3 ) 
The values of A, obtained by introducing into this expression the 
concentrations of the undissociated portions of the free acid, 
neutral and acid sulphates are given in the next three tables. 
They correspond to the tables given on p. 506, the probable mean 
value of A for each series being found as before by assigning to 
each individual constant its own “ weight.” 
