[19]. The pile and trough, are both sometimes denominated Batteries.

[20]. Volta by the aid of his condenser of electricity, discovered that the two extremities of his pile were in opposite states; the zinc end was always plus or positive, and the silver end, minus or negative.

[21]. This sub-acid taste, is rendered much more distinct by an instrument invented by Professor Robinson, and described by him in a letter to Dr. Fowler, dated 28th May, 1793. It is made by placing alternately a number of small circular pieces of zinc, with as many pieces of silver of the same size, in the form of a rouleau. It is to be used by placing it laterally upon the tongue.

[22]. With regard to the similarity between the taste of Galvanism and that of electricity, Dr. Fowler observes that he found considerable difference between them—. “Both (says he) are sub-acid, but as unlike each other, as the taste of vinegar is to that of diluted vitriolic acid.”

This sensation, produced upon the tongue by Galvanism, is most distinct when the tongue is of its usual temperature, and the metals of the same temperature with it. When either the tongue, the metals, or both, are heated or cooled, as far as can be borne without inconvenience, scarcely any taste is produced.

[23]. This is the explanation given by Mr. Wilkinson, but we think it probable that this effect is altogether chemical.

TRANSCRIBER’S NOTES