Page:The fundamental laws of electrolytic conduction.djvu/29

 small retort containing the two electrodes; the neck is narrow, and sufficiently long to deliver gas issuing from it into a jar placed in a small pneumatic trough. The electrode chamber, sealed hermetically at the part held in the stand, is 5 inches in length and 0.6 of an inch in diameter; the neck is about 9 inches in length and 0.4 of an inch in diameter internally. The figure will fully indicate the construction.

It can hardly be requisite to remark, that in the arrangement of any of these forms of apparatus, they, and the wires connecting them with the substance, which is collaterally subjected to the action of the same electric current, should be so far insulated as to insure a certainty that all the electricity which passes through the one shall be transmitted through the other.

Next to the precaution of collecting the gases, if mingled, out of contact with the platinum, was the necessity of testing the law of a definite electrolytic action, upon water at least, under all varieties of condition; that, with a conviction of its certainty, might also be obtained a knowledge of those interfering circumstances which would require to be practically guarded against.

The first point investigated was the influence or indifference of extensive variations in the size of the electrodes, for which purpose instruments like those last described were used (Figs. 5, 6, and 7). One of these had plates 0.7 of an inch wide and nearly 4 inches long; another had plates only 0.5 of an inch wide and 0.8 of an inch long; a third had wires 0.02 of an inch in diameter and 3 inches long; and a fourth, similar wires only half an inch in length. Yet when these were filled with dilute sulphuric acid, and, being placed in succession, had one common current of electricity passed through them, very nearly the same quantity of gas was evolved in all. The difference was sometimes in favor of one, and sometimes on the side of another; but the general result was that the largest quantity of gases was