Page:The fundamental laws of electrolytic conduction.djvu/73

. A silver dish, which served as cathode, contained a solution of silver nitrate, into which dipped a silver plate as anode. The latter was wrapped around with a linen cover to prevent little particles, which easily come off during solution of the anode by the liberated anion N&#8411;&#8411;, from falling into the dish, and thus increasing the weight of the reduced silver. The first salt which I decomposed was copper sulphate, with which Daniell and Miller also worked, and which possesses special interest on account of its application in galvanoplasty. It is the most convenient electrolyte for our experiments, for, as is well known, copper deposits coherently, and consequently adheres firmly to the surface of the silver cone.

The solution which was subjected to electrolysis was prepared by diluting a more concentrated one to about twice its volume. Its specific gravity at 4.9° C. was 1.1036, and it contained 1 part S Ċu to 9.56 parts water, or 1 part (S Ċu + 5 Ḣ) to 5.75 parts water.

The electrolysis was carried out at the temperature 4.7° C., and was effected by means of a small Grove cell. The current continued four hours and reduced 1.008 gr. Ag in the voltameter, or 0.0042 gr. Ag per minute. This quantity of silver is equivalent to 0.2955 gr. Cu.

There was deposited on the silver cone, however, 0.2975 gr. Cu.

The difference, 0.002 gr., arises without doubt from an oxydation of the copper; we base all calculations on values deduced from results obtained by the silver voltameter.

The solution about the cathode contained:

It was therefore diluted by an amount 0.2646 gr. Ċu = 0.2112 Cu.

The Ċu was precipitated in the usual way by caustic potash, from a boiling solution.

The amount of transferred copper is therefore