6 i 4 Stiles and J0rgensen.—Studies in Permeability. II. 
R. W. Paul, and which proved a much more convenient and sensitive 
arrangement. 
The hydrogen-ion concentrations of the various solutions were then 
calculated according to the formula 
A RT. C 0 
e i~ e o = 2*3036 -- log -g? 
where e 0 is the E.M.F. given with a liquid of hydrogen-ion concentration 
C 0 and e 1 the E.M.F. given with a liquid of hydrogen-ion concentration 
C r R is the gas constant, T the absolute temperature, and F signifies 
1 faraday (= 96580 coulombs). 
That the apparatus was giving correct readings was tested by the 
use of different concentrations of acids of known strength. 
The Results. 
Experiments were conducted at four different temperatures, o°C., 
io°C., 30 °C., 30°C. The amounts of acid absorbed by the tissue after dif¬ 
ferent lengths of time at these various temperatures are indicated in the 
following tables. The second column shows the increase of the E.M.F. 
at the surface of the hydrogen electrode in each of the acid solutions as 
compared with that in the case of the original 00011 N acid. The third 
column shows the concentration of the acid as calculated from this E.M.F., 
and the next column the actual absorption. The numbers in the last 
column we shall refer to later. 
Temp. o°C. 
Increase of 
E.M.F. in volts. 
Relative Concentration 
Relative quantity 
Time in hours. 
(C) of Hydrogen Ion 
in Solution. 
of Hydrogen Ion 
absorbed. 
-Log C. 
0*0 
0*0 
1*000 
0*0 
0*0 
3.0 
0*0069 
0*751 
0*249 
0*124 
6*o 
0*0120 
o*6io 
0*390 
0-215 
8*o 
0*0172 
o*493 
0*507 
0*307 
8-o 
0*0173 
0.491 
0*509 
0*309 
Temp. 
0 
O 
Time in hours. 
Increase of 
E.M.F. in volts. 
Relative Concentration 
(C) of Hydrogen Ion 
in Solution. 
Relative quantity 
of Hydrogen Ion 
absorbed. 
— Log. C. 
0*0 
0*0 
1 *ooo 
0*0 
0*0 
o*5 
0*0035 
0*870 
0*130 
0*060 
0*5 
0*0027 
0*898 
0*102 
0*048 
1*0 
0*0062 
0*781 
0*219 
0*107 
2*0 
0*0084 
0*709 
0*291 
o-i49 
2*0 
0*0084 
0*709 
0*291 
0*149 
2> 5 
0*0145 
0*561 
0-439 
0*251 
4*° 
0*0180 
0*488 
0*512 
0*312 
5*o 
0*0231 
0*399 
o*6oi 
o-399 
5*o 
0*0202 
0*447 
o-553. 
0-350 
6-o 
0*0256 
0*361 
0*639 
o-443 
6-o 
0*0249 
0*370 
0*630 
0*432 
