| Cr 
System TRE = Ee Remarks 
Calculated Capillary 
from spec. Electrom 
: ; conductivity ' 
— === - - = 
0.5 m. pyrocatechin [04 10-4] 14 X10 4 | Thedataasto 
| the specific con- 
|; 25110 2 | ductivity are 
64 X , taken from ob- 
SOR, servations pu- 
blished in the 
Recueil 30, 403 
0.5 m. pyrocat + 0.5 mH3BO3 ONS Om? 
25710 2 (1911) and from 
WED ey ‚a few measure- 
HOSS oe ‘ments mention-| 
ed below. 
0.5 m. pyrogallol+-0.5 mH;BO; | 0.16 >< 10 
0.5 m. hydroxy-hydroquinone+- | al 
| +0.5 m. HBO, 0.104 X 10 | 
| | | 
‚0.25 m. hydroxy- hydroquinone + 5 3 5 
| £0.25 m. H,BO, 0.51 > 10 SEL 200 
te 
NE 
fae) 
el 
EN 
ZA 
ee) 
| 
We have found the cause of this deviation as follows. 
When the vessel with the hydrogen-pyrocatechin-boric acid electro- 
lyte had stood for a day, the volume of the hydrogen had percep- 
tibly diminished and after a week the gas had almost entirely 
disappeared. 
In connexion with the presence of the platinum rod in the pyro- 
eatechin solution above which is found an atmosphere of hydrogen 
and the consequent possible catalytic hydrogenation of the pyro- 
catechin, we may no doubt attribute the disappearance of the 
hydrogen to the reaction: 3 H, + C,H,(OH), = C,H,,(OH) . 
Consequently there is no equilibrium at the hydrogen electrode 
and as, owing to the reaction, hydrogen is removed from the 
platinum, the hydrogen pressure may no longer be supposed to 
be equal to one atmosphere but must be smaller and dependent on 
the velocity with which the loss from the gaseous space can again 
be replenished. 
If we wrongly put the hydrogen pressure = 1 atm. we will, in 
consequence thereof, find inconstant and exaggerated valnes for the 
hydrogen-ion concentrations. 
For in the relation = el In ee In V Py» may no longer be 
F CH: 
put =O, it becomes negative and £ is thus found too small. Hence, 
E 
the absolute value of the negative quantity log Ch unne 
becomes too small and the concentration itself too large. 
