9 6 Haynes.—A Criticism of Beutner s Theory of the 
tance for physiology, and no further justification will be needed for a careful 
review of the evidence upon which it is based. 
The systems investigated by Beutner are of two general types, repre¬ 
sented by the following schemes : 
System /. 
D 
A 
C 
B 
f 
Hg 
MiXj 
M 2 X 2 
Hg 
KC 1 N/i 
water 
oil 
water 
KC 1 N/i 
[c] 
[c] 
System II. 
I) 
A 
C 
1 
> 
) 
I 
Hg 
MX 
MX 
Hg 
KC 1 N/i 
water 
oil 
water 
KC 1 N/i 
M 
[c 2 ] 
In these systems the potassium chloride in contact with the electrodes 
is frequently replaced by sodium chloride ; MX represents a salt of which M 
is the cation and X the anion, and c, c v c 2 in square brackets represent 
concentrations. It will be seen that System I consists of different salts 
of the same concentration in contact with ‘ oil’; System II of the same salt 
at different concentrations. In experimenting with systems of the type of 
System I, Beutner’s general practice was to use salts having a common 
cation or a common anion. In this case M 1 X 1 , M 2 X 2 will be replaced by 
MjX, M 2 X, or MX, MX 2 . The ‘ oil ’ is a liquid which may be of very 
various chemical composition, ranging from acidic substances such as 
salicyclic aldehyde or benzaldehyde to definitely basic substances such as 
tf.-toluidine. 
In both systems potential differences may arise at the boundaries A, B, 
and C. Those at D and E Beutner considers to be obliterated by the more 
concentrated salt solutions in contact with the electrodes. 
Beutner follows Haber’s method in deriving the theory of such systems 
from a consideration of the following : 
AC B 
metal 
aqueous solution 
solution in oil of the same salt in 
of salt 
equilibrium with the aqueous 
solution. 
metal 
The e.m.f. of this system is zero, since work cannot be done by transfer¬ 
ence of salt across the boundary C ; hence the potential at C is equal and 
opposite to the sum of the potentials at A and B. If, therefore, the hypo¬ 
thesis of solution pressure is extended to oils, the boundary potential can be 
expressed as : 
Ec — R T log ^ x const ... (i) 
C ‘ oil 
C water, C ‘ oil ’, representing the concentrations of the cation in the two 
liquids. 
