Hind. — Studies in Permeability. IIL 
229 
similar to that in the case of the strong mineral acids, but as Fig. 5 indicates 
the decrease in conductivity is less, which may be due to a smaller absorp- 
tion of hydrogen ions, or to the greater exosmosis of electrolytes. 
> 
=3 
T3 
C 
o 
O 
S-oooi 
L. 
O 
_a > 
LtJ 
(D 
C/5 
CO 
CD 
£_ 
O 
c 
•0002 
•0003 
TA. 
2000 
vy. 
\000_ 
ty 
600 
Time in Hours 
Fig. 5. Potato in Oxalic Acid. 
Formic Acid. 
Series 7 and 8. — In the case of formic acid considerably different 
results were obtained. Conductivity measurements of the external solution 
N N N 
were made with acid of original concentration — , , . In all 
& 500 1000 ’ 2000 
cases the conductivity showed at first a slight decrease, which speedily gave 
place to a rapid increase, this increase being greater the higher the con- 
centration of the acid (cf. Fig. 6). 
Measurements of the actual concentration of the hydrogen ion were 
N 
made in the case of acid. 
1000 
Fig. 7 indicates the course of thfe absorption. It will be observed that 
during the first few hours the hydrogen ion is absorbed at almost the same 
rate as the hydrogen ions of nitric acid. After a time, however, a remark- 
able change occurs. This consists in the concentration of the hydrogen ion 
of the external solution increasing, a phenomenon which was never observed 
in the case of the inorganic acids. 
R 
