220 REPORT—1890. 
into a number of ions, thus into two in the case of KCl, into three in the 
eases BaC], and K,SO,; the dissociation detaches but preserves intact 
a multivalent complex ion from a number of monovalent ones, and also 
separates the monovalent ones one from another. Ostwald, in his for- 
mula, refers only to binary compounds, each molecule of which is resolved 
into two ions; but in considering the applicaticn of the dissociation hypo- 
thesis to chemistry in the paper already referred to,! he touches upon an 
interesting point. He lays down the principle that chemical reactions 
consist in the exchange of ions, and therefore take place exclusively 
between ions. Thus a number of chlorine compounds give no reaction 
with silver because the chlorine does not appear as anion. This prin- 
ciple enables one to distinguish between salts of composite acids (as, for 
instance, Na,PtCl, and K,Fe(CN),, which show such reactions as are 
compatible with splitting up into ions Na and PtCl, and K and Fe(CN), 
respectively) and true double salts, as the alums, which in solution are 
resolved, and do not exist as double salts. 
These hypotheses can be verified by the depression of the freezing- 
point in the solutions, for the number of the ions is different in the two 
cases. Thus the double salt 3K,C,0,+Cr,(C,0,), would form fourteen 
ions, whereas if it were really 2K3,CrC,O,,. only eight ions would be 
formed from the same molecule. 
But perhaps the most interesting, as being the least evident sugges- 
tion, is that which, based on reactions similar to the slow precipitation of 
silver chloride with separation of glycolic acid from monochlor-acetate 
solution, is thus expressed (p. 598) : ‘ In order to express this consideration 
in general terms we must say that an electrolyte may ultimately split up 
in different directions. Usually one definite direction is far away the most 
prominent, and the corresponding reactions are completed in immeasur- 
ably short time ; to the other directions correspond processes which pro- 
ceed slowly. Since the organic compounds in particular, in so far as 
they are not salts, belong entirely to the class of non-electrolytes in the 
ordinary sense, and are therefore not split into ions to an appreciable 
extent, we obtain on these grounds an explanation of the slowness of the 
march of the processes so characteristic of this department. It is very 
probable that tho effect of the accelerators, of the hydrogen-chloride in 
the formation of ethers, the ferric chloride in chlorination, the acetic 
ether in the action of sodium, and so on, consists in nothing else than the 
formation of composite electrolytes.’ 
In the July number of the ‘Zeitschrift fiir physikalische Chemie,’ 
1889 (p. 96), Arrhenius has given some interesting developments of the 
dissociation theory. He first of all gives the molecular conductivities of 
a number of salts at 18° C. and 52° C. and the temperature coefficients 
deduced therefrom, for a number of solutions of different concentration, 
having in view the effects which may be due to the alteration of the dis- 
sociation ratio with temperature. Then taking, as Ostwald had done 
(p. 217), the equation of gaseous dissociation Pup? KT and also the 
equation 
alee 
d. log, B.A w 
dt Ree 
 Zeitschr. 3, p. 596. 
