873.  But admitting that chemical action is the source of electricity, what an infinitely small fraction of that which is active do we obtain and employ in our voltaic batteries!  Zinc and platina wires, one-eighteenth of an inch in diameter and about half an inch long, dipped into dilute sulphuric acid, so weak that it is not sensibly sour to the tongue, or scarcely to our most delicate test-papers, will evolve more electricity in one-twentieth of a minute (860.) than any man would willingly allow to pass through his body at once.  The chemical action of a grain of water upon four grains of zinc can evolve electricity equal in quantity to that of a powerful thunder-storm (868. 861.).  Nor is it merely true that the quantity is active; it can be directed and made to perform its full equivalent duty (867. &c.).  Is there not, then, great reason to hope and believe that, by a closer experimental investigation of the principles which govern the development and action of this subtile agent, we shall be able to increase the power of our batteries, or invent new instruments which shall a thousandfold surpass in energy those which we at present possess?

874.  Here for a while I must leave the consideration of the definite chemical action of electricity.  But before I dismiss this series of experimental Researches, I would call to mind that, in a former series, I showed the current of electricity was also definite in its magnetic action (216. 366. 367. 376. 377.); and, though this result was not pursued to any extent, I have no doubt that the success which has attended the development of the chemical effects is not more than would accompany an investigation of the magnetic phenomena.

Royal Institution, December 31st, 1833.

EIGHTH SERIES.

S14. On the Electricity of the Voltaic Pile; its source, quantity, intensity, and general characters. P i. On simple Voltaic Circles. P ii. On the intensity necessary for Electrolyzation. P iii. On associated Voltaic Circles, or the Voltaic Battery. P iv. On the resistance of an Electrolyte to Electrolytic action. P v. General remarks on the active Voltaic Battery.

Received April 7,—­Read June 5, 1831.

P i. On simple Voltaic Circles.

875.  The great question of the source of electricity, in the voltaic pile has engaged the attention of so many eminent philosophers, that a man of liberal mind and able to appreciate their powers would probably conclude, although he might not have studied the question, that the truth was somewhere revealed.  But if in pursuance of this impression he were induced to enter upon the work of collating results and conclusions, he would find such contradictory evidence, such equilibrium of opinion, such variation and combination of theory, as would leave him in complete doubt respecting what he should accept as the true interpretation of nature:  he would be forced to take upon himself the labour of repeating and examining the facts, and then use his own judgement on them in preference to that of others.