Contents Index

An Account of a Method of constructing simple and compound Galvanic Combinations without the use of metallic Substances, by means of Charcoal and different Fluids (1802).1

in The Collected Works of Sir Humphry Davy, ed. John Davy (London: Smith, Elder and Co., 1839), II, 209-10.

{209} 1. If a piece of well burned charcoal be brought in contact at one of its surfaces with a portion of water, and at another surface with a portion of nitric acid, a simple galvanic combination will be formed when the two fluids are connected together. And the powers of it are demonstrated by its agencies upon the limbs of frogs, and by its effects upon the organs of sense.

2. A compound galvanic combination, or a galvanic battery may be formed from a number of series, composed of the same substances, but in this case the fluid elements of each series not being immediately in contact, must be connected with similar elements in other series in an order of regular alternation, such as water, charcoal, acid; water, charcoal, acid; and so on.

3. The best mode that has yet occurred of constructing galvanic batteries with charcoal is by means of a number of glasses which are made to contain alternately nitrous acid and water, and which are connected in pairs by means of moistened cloth. The pieces of {210} charcoal used are made from very dense wood, such as box or lignum vitae; and in this case the fluids will not penetrate into them by capillary attraction much beyond the places of their primary contact. Their forms are those of arcs, so that each pieces connects together two glasses; but in instances where single pieces of charcoal cannot be obtained of the proper shape, two long and thin slips may be fastened together by silk, so as to form the angle necessary to their insertion into the glasses.

4. Twenty series in a battery of this kind produce sensible but feeble shocks, and when a single metallic series with a gold wire and two glasses of water is substituted for one of the primary series, hydrogen is given out by the metallic point in the glass of water in the place of the acid, whilst oxygen is evolved from the point in the other glass.

5. In the galvanic batteries with charcoal, sulphuric acid may be substituted for nitric acid; and solution of sulphuret of potash for the water; without any material alteration in the nature of the agency; the solution of the sulphuret indeed seems, in some measures, to increase its intensity, and combinations containing this substance, dense charcoal and concentrated nitric acid, appear to be superior in activity to similar combinations containing copper, and the same fluid elements, and to be nearly equal to those composed of zinc, silver and water.

January 9, 1802.

Notes

1. [From Journals of the Royal Institution, vol. i.]