Page:The fundamental laws of electrolytic conduction.djvu/37

 the latter object the volta-electrometer (Fig. 7) is most accurate, as its gas can be measured over water, whilst the others retain it over acid or saline solutions.

I have not hesitated to apply the term degree in analogy with the use made of it with respect to another most important imponderable agent—namely, heat; and as the definite expansion of air, water, mercury, etc., is there made use of to measure heat, so the equally definite evolution of gases is here turned to a similar use for electricity.

The instrument offers the only actual measurer of voltaic electricity which we at present possess. For without being at all affected by variations in time or intensity, or alterations in the current itself, of any kind, or from any cause, or even of intermissions of action, it takes note with accuracy of the quantity of electricity which has passed through it, and reveals that quantity by inspection; I have therefore named it a.

Another mode of measuring volta-electricity may be adopted with advantage in many cases, dependent on the quantities of metals or other substances evolved either as primary or as secondary results; but I refrain from enlarging on this use of the products, until the principles on which their constancy depends have been fully established.

By the aid of this instrument I have been able to establish the definite character of electrochemical action in its most general sense; and I am persuaded it will become of the utmost use in the extensions of science which these views afford. I do not pretend to have made its detail perfect, but to have demonstrated the truth of the principle, and the utility of the application.

[Section VI., including thirteen pages, "On the Primary and Secondary Character of the Bodies Evolved at the Electrodes" is here omitted.]

In the third series of the Researches, after proving the