138 CONDUCTIVITY OF AQUEOUS SOLUTIONS.—BARNES. 
in all the calculated values of the conductivity. There is also (2) 
the possibility referred to above, of the sulphuric acid breaking 
up not only into ions of 2 H and S8O,, but also into H and 
iSO; 
It is also possible by plotting the above series to obtain series 
of mixtures having a constant concentration for the constituent 
hydrochloric acid solutions and variable concentrations for the 
sulphuric acid constituent solutions; and it will be found in 
series of this kind that the same regular progression is exhibited 
asin theabove. It may be well to note that in the last three 
series of the above Table where the sign of the difference 
changes, this change happens for all when the average concen- 
tration of the mixture is about 0.6 gramme-equivalents. 
Finally, since my experiments are estimated as affected by 
an error which may amount to about 0.3 per cent., it 1s seen 
in the table that as the differences for the three last series are all 
within or in a few cases but little beyond this error, it may be 
concluded that the conductivity of mixtures of dilute solutions 
of hydrochloric and sulphuric acid can be calculated within the 
limit of my experimental error, by the expression of the dissocia- 
tion theory and on the assumption that the sulphuric acid dis- 
sociates into 2 H and SO, as ions, up to an average concentration 
of about 0.5 in eases in which the concentration with respect to 
sulphurie acid is relatively large, and up to an average concen- 
tration of about 0.9 in cases in which the concentration with 
respect to this acid is relatively small. 
