218 REPORT—1890. 
on the number of molecules dissociated, and that the dissociation is com- 
plete in infinite dilution, we get (p. 277) 
Poa Mon— Hn) 
Peo” bbe 
where p» is the limiting maximum of molecular conductivity, », the 
molecular conductivity at volume v per gramme-molecule, and c’ is con- 
stant at constant temperature. 
From this formula the above six statements may be immediately 
deduced. It also furnishes a new basis of comparison; for writing 
m for p/p we get the following new relation between molecular con- 
ductivities at different dilutions : 
m 
G—m)o_ 
2 
ke 
Ostwald gives a number of values of the constant i for acetic acid, 
angelica acid, a-chlorisocrotonic acid, o-oxysalicylic acid, and the num- 
bers agree quite satisfactorily ; according to Ostwald, more nearly than 
the corresponding numbers for the formula as applied to gaseous disso+ 
ciation.! 
We give one table referring to butyric acid : 
C’ (corrected for high 
v KB k pressures and changes 
| of viscosity ) 
2 1:726 071152 0:1538 
4 2°648 0:1359 | 071554 
8 3870 0°1475 | 0:1549 
16 5:554 0:1509 0:1557 
32 7874 0°1530 | 071551 
64 11:16 0°1545 0:1560 
128 15°67 0:1541 0:1550 
256 22°67 0:1560 0:1560 
512 30°73 0°1558 | 0:1558 
1,024 42°40 0°1535 0°1535 
The column headed & should give the same values throughout ; the 
earlier values are evidently too small, but the differences are accounted 
for on the hypotheses (1) that at high concentrations the osmotic pressure 
is very high, viz. 24 atmospheres in a normal solution (1 gm.-molecule in 
1 litre) ; at these high pressures the gaseous laws do not hold, and a cor- 
rection term must be introduced, as in the case of gases by Van der 
Waals, which alters the formula to the form ese =C(v—b). (2) The 
—im 
conductivity depends not only on the dissociation but also on the fluidity 
of the solution; hence, in order to compare the conductivities for the 
purpose of this formula, which takes account of the dissociation alone, 
the observed conductivity must be reduced to a theoretical conductivity 
1 In three papers in vol. iii. of the Zeitschr. fiir ph. Chem. pp. 170, 241, 369, 
Ostwald has determined the value of the constant % in the above formula for a large 
number of organic acids. The values tabulated are those of K=1002%7(p. 174). An 
index of the acids thus investigated is given J.c., p. 418. The physical meaning of 
the constant is that at concentration 2% half of the acid is dissociated. 
di, ange. xe we ee eee 
. 
