1651 
8 0.480 —0.377 =F 
log Cy = — Ser Maa 2.42 — 0,58-—3 
JUD E 
Ca 3:8 Sa 10a: 
The specifie conductivity of this solution — 700 X 10 *. 
From this 
700 X 10-3 
— Nese On aides 
Ze S60 a ee 
Hydrogen-ion concentration of N/1O lactic acid. 
242 
EMF (see above) = —— X 1.0177 = 0.479 v 
514 
log Cp = — 2.40 and Cg: —= 4.0 x 107° 3 
: £ 1426 X 10 ? 
Cond. of this solution = 1426105 Cyr = — ETR 320 << Oms: 
no 
Hydrogen-ion concentration of N/10 lactic acid +0.5 mol. H,BO,. 
232.7 
EMF — SS X 1.0177 = 0.461 » 
5138.9 
log Cy = —2.10 and Cg-= 7.94 X 1073 
Calculated from the specific conductivity — 263210 ° we get 
et OS eet 
33000 
Although the agreement in these complex boric compounds is 
certainly not perfect, it may, considering the relatively small sensi- 
tiveness of the capillary-eleetrometrie method and the uncertainty 
as to the value (380) for ä7 + y,, be called satisfactory. 
In any case, the increase in conductivity of borie acid by mannitol 
and by lactic acid is to be attributed to the formation of a complex 
mannito-(lacto)-boric acid which is more strongly dissociated than one 
of the components. 
Quite different were the results of the measurements executed 
with solutions of pyrocatechin, pyrogallol and hydroxy-hydroquinone. 
The following results were obtained here: (see table p. 1652). 
Not only was there not found any agreement between the values 
obtained according to the two methods, but the duplicate determ- 
inations also showed enormous differences. 
It is certain that the values according to the capillary-electro- 
metric method were found far too high. 
Hence, there must be a source of error in this method when 
applied to the polyphenols as electrolyte. 
106 
Proceedings Royal Acad. Amsterdam. Vol. XVIII. 
