PROFESSOR DANIELL ON THE ELECTROLYSIS OF SECONDARY COMPOUNDS. 219 
the results of my next experiment as furnishing a key to the mystery which has oc- 
casioned me so much perplexity and labour. 
Experiment 38. — I was naturally anxious to complete my electrical examination of 
the sulphates by the electrolysis of the bi-salts of this class, and for this purpose I 
made a strong solution of pure crystallized bi-sulphate of potassa; and carefully 
ascertained its neutralizing power, by the alkalimeter, and also, by evaporation and 
ignition with carbonate of ammonia, the quantity of neutral sulphate which a certain 
measure of it contained. I then exposed an equal measure of the solution to the vol- 
taic current in each of the arms of the double diaphragm cell till 70'8 cubic inches 
of the mixed gas had been collected. Half of the solutions from the zincode and 
platinode were then separately neutralized, and half evaporated and ignited. 
Upon a calculation for the whole quantity, the zincode solution appeared to have 
gained eighteen grains of acid, and the platinode to have lost nineteen grains, while 
the zincode had lost fifteen grains of neutral sulphate, which are equivalent to 8 - 2 
grs. of potassa, and the platinode had gained something less. 
Experiment 39. — The experiment, the results of which appear to me to be extremely 
important, was immediately repeated, and the losses and gains of the zincode and 
platinode solutions corresponded still more closely than before. With regard to the 
acid, the gain of the zincode was eighteen grains, the loss of the platinode nineteen 
grains. With regard to the potassa, the gain of the platinode was 9'9 grs., and the 
loss of the zincode exactly equal. 
Hence it appears that the law of the electrolysis of the bi-salt is very different from 
that of the neutral salt : the solution conducted very well, but as estimated by the 
potassa transferred to the platinode, not more than one fifth of an equivalent was de- 
composed for an equivalent of hydrogen evolved at the same electrode. This was 
accompanied by the transfer of half an equivalent of acid to the zincode, where a 
whole equivalent of oxygen was also given off. 
I think that we cannot hesitate to admit that, in this case, the current divided 
itself between two electrolytes, and that a part was conducted by the neutral sulphate 
of potassa, and a larger part by the sulphuric acid and water, after the manner of the 
solutions upon which we have dwelt so long. It is a well known fact that the voltaic 
current will divide itself between two or more metallic conductors in inverse propor- 
tion to the resistance which each may offer to its course ; and that it does not in such 
cases choose alone the path of least resistance; and, in a former communication* 
to you, I pointed out some curious instances of diverted currents in which liquid elec- 
trolytes were concerned. I am not aware that such a division of a current between 
two electrolytes in the same solution has ever before been pointed out, but analogy 
would lead one to expect it. 
With this new view let us now revert first to the experiments with the dilute sul- 
phuric acid. If we regard this acid as a mixture of the two electrolytes, oxisulphion 
* Philosophical Transactions, for 1837, p. 119. 
2 f 2 
