MEMOIRS ON THE FUNDAMENTAL
trometer, showing that in all the vessels the current had decomposed an equal quantity of water. In this trying case, therefore, the chemical action of electricity proved to be perfectly definite.
A similar experiment was made with muriatic acid diluted with its bulk of water. The three positive electrodes were zinc, silver, and platina; the first being able to separate and combine with the chlorine without the aid of the current; the second combining with the chlorine only after the current had set it free; and the third rejecting almost the whole of it. The three negative electrodes were, as before, platina plates fixed within glass tubes. In this experiment, as in the former, the quantity of hydrogen evolved at the cathodes was the same for all, and the same as the hydrogen evolved in the volta-electrometer. I have already given my reasons for believing that in these experiments it is the muriatic acid which is directly de- composed by the electricity; and the results prove that the quantities so decomposed are perfectly definite and proportionate to the quantity of electricity which has passed.
In this experiment the chloride of silver formed in the second basin retarded the passage of the current of electricity, by virtue of the law of conduction before described,[1] so that it had to be cleaned off four or five times during the course of the experiment; but this caused no difference between the results of that vessel and the others.
Charcoal was used as the positive electrode in both sulphuric and muriatic acids; but this change produced no variation of the results. A zinc positive electrode, in sulphate of soda or solution of common salt, gave the same constancy of operation.
Experiments of a similar kind were then made with bodies altogether in a different state—i.e., with fused chlorides, iodides, etc. I have already described an experiment with fused chloride of silver, in which the electrodes were of metallic silver, the one rendered negative becoming increased and lengthened by the addition of metal, whilst the other was dissolved and eaten away by its abstraction. This experiment was repeated, two weighed pieces of silver wire being used as the electrodes, and a volta-electrometer included in the circuit. Great
care was taken to withdraw the negative electrode so regularly
34
- ↑ [See foot-note, p. 27.]
