ELECTROLYSIS OF SECONDARY COMPOUNDS. 
3 
Let A, B, C, &c. in the preceding diagram represent a series of particles of chlorine, 
a, b, c, &c. a series of particles of potassium in combination with the particles of 
chlorine in the row above them, X, Y a central line or diaphragm, and Z and P the 
electrodes. If 1 represent the arrangement before the current passes, the particles A 
and a, B and b, &c. being combined to form compound particles of chloride of potas- 
sium, 2 would represent the arrangement after a single equivalent of eacli ion had 
been disengaged at the electrodes. Each particle would thus necessarily have moved 
forward half a step, combining with the next adjacent particle, so that B a, C b, D c, 
&c. would now form the chain between the electrodes. If another equivalent be now 
supposed to be set free at each electrode, one particle of each ion would have passed 
the central line, one equivalent would thus be transferred, whilst two had been dis- 
engaged, as in fig. 3. 
In the instances above referred to, the transfer of one quarter of an equivalent 
represented half of an equivalent of the hydrates respectively electrolysed. Little 
stress however need be laid upon this correction, inasmuch as we shall presently 
show that the hypothesis upon which it is founded, although generally received, is 
itself destitute of foundation. 
1. Our first object was to ascertain more clearly than had yet been done, the in- 
fluence of water in the aqueous solution of an electrolyte, by comparison with the results 
of the electrolysis of the same compound when in the state of igneous fusion. It had 
been already determined, that with regard to the chlorides no difference occurred, and 
that the amounts of chlorine evolved in the same circuit from fused chloride of lead *, 
and from dissolved chloride of sodium and muriate of ammonia, were the same-f'. In 
the last case, ammonia and hydrogen were evolved at the platinode in equivalent 
proportions to the chlorine at the zincode. Here a compound cation (NH 4 ) was 
separated from an elementary anion. 
When nitrate of silver in solution is subjected to electrolysis, the simple cation, 
silver, separates from the compound anion (N0 6 ), and upon substituting the salt in 
a state of fusion, for the solution, we obtained the same result. No gas was evolved, 
but crystallized metallic silver was deposited upon a silver platinode, which gra- 
dually increased in length, as it was slowly withdrawn from the liquid salt, just as in 
the analogous experiment with fused chloride of silver, devised by Dr. Faraday. 
Nitrous fumes were at the same time given off from the platinum zincode in abun- 
dance. From these experiments it is evident that neither the grouping of a com- 
pound cation, nor of a compound anion, is necessarily altered by water in the transit 
to their respective electrodes. 
2. We now turned our attention to that most interesting group of salts, the phos- 
phates, which has been so ably discussed by Professor Graham ; not without hopes 
of confirming by electrolysis the beautiful theory of their constitution, which he has 
b 2 
* First Letter, p. 108. 
f Ibid. p. 110. 
