Mr. Highton, C.E., has made a battery which exposes a surface of only 1/100th part of an inch: it consists of but one cell; it is less than 1/10000th part of a cubic inch, and yet it produces electricity more than enough to overcome all the resistance in the inventor’s brother’s patent Gold-leaf Telegraph, and works the same powerfully. It is, in short, a battery which, although it will go through the eye of a needle, will yet work a telegraph well. Mr. Highton had previously constructed a battery in size less than 1/40th of a cubic inch: this battery, he found, would for a month together ring a telegraph-bell ten miles off.
ELECTRIC INCANDESCENCE OF CHARCOAL POINTS.
The most splendid phenomenon of this kind is the combustion of charcoal points. Pointed pieces of the residuum obtained from gas retorts will answer best, or Bunsen’s composition may be used for this purpose. Put two such charcoal points in immediate contact with the wires of your battery; bring the points together, and they will begin to burn with a dazzling white light. The charcoal points of the large apparatus belonging to the Royal Institution became incandescent at a distance of 1/30th of an inch; when the distance was gradually increased till they were four inches asunder, they continued to burn with great intensity, and a permanent stream of light played between them. Professor Bunsen obtained a similar flame from a battery of four pairs of plates, its carbon surface containing 29 feet. The heat of this flame is so intense, that stout platinum wire, sapphire, quartz, talc, and lime are reduced by it to the liquid form. It is worthy of remark, that no combustion, properly so called, takes place in the charcoal itself, which sustains only an extremely minute loss in its weight and becomes rather denser at the points. The phenomenon is attended with a still more vivid brightness if the charcoal points are placed in a vacuum, or in any of those gases which are not supporters of combustion. Instead of two charcoal points, one only need be used if the following arrangement is adopted: lay the piece of charcoal on some quicksilver that is connected with one pole of the battery, and complete the circuit from the other pole by means of a strip of platinum. When Professor Peschel used a piece of well-burnt coke in the manner just described, he obtained a light which was almost intolerable to the eyes.
VOLTAIC ELECTRICITY.
On January 31, 1793, Volta announced to the Royal Society his discovery of the development of electricity in metallic bodies. Galvani had given the name of Animal Electricity to the power which caused spontaneous convulsions in the limbs of frogs when the divided nerves were connected by a metallic wire. Volta, however, saw the true cause of the phenomena described by Galvani. Observing that the effects were far greater when the connecting medium consisted of two different kinds of metal, he inferred that the principle of excitation existed in the metals, and not in the nerves of the animal; and he assumed that the exciting fluid was ordinary electricity, produced by the contact of the two metals; the convulsions of the frog consequently arose from the electricity thus developed passing along its nerves and muscles.
In 1800 Volta invented what is now called the Voltaic Pile, or compound Galvanic circle.
The term Animal Electricity (says Dr. Whewell) has been superseded by others, of which Galvanism is the most familiar; but I think that Volta’s office in this discovery is of a much higher and more philosophical kind than that of Galvani; and it would on this account be more fitting to employ the term Voltaic Electricity, which, indeed, is very commonly used, especially by our most recent and comprehensive writers. The Voltaic pile was a more important step in the history of electricity than the Leyden jar had been—Hist. Ind. Sciences, vol. iii.
No one who wishes to judge impartially of the scientific history of these times and of its leaders, will consider Galvani and Volta as equals, or deny the vast superiority of the latter over all his opponents or fellow-workers, more especially over those of the Bologna school. We shall scarcely again find in one man gifts so rich and so calculated for research as were combined in Volta. He possessed that “incomprehensible talent,” as Dove has called it, for separating the essential from the immaterial in complicated phenomena; that boldness of invention which must precede experiment, controlled by the most strict and cautious mode of manipulation; that unremitting attention which allows no circumstance to pass unnoticed; lastly, with so much acuteness, so much simplicity, so much grandeur of conception, combined with such depth of thought, he had a hand which was the hand of a workman.—Jameson’s Journal, No. 106.
THE VOLTAIC BATTERY AND THE GYMNOTUS.
“We boast of our Voltaic Batteries,” says Mr. Smee. “I should hardly be believed if I were to say that I did not feel pride in having constructed my own, especially when I consider the extensive operations which it has conducted. But when I compare my battery with the battery which nature has given to the electrical eel and the torpedo, how insignificant are human operations compared with those of the Architect of living beings! The stupendous electric eel in the Polytechnic Institution, when he seeks to kill his prey, encloses him in a circle; then, by volition, causes the voltaic force to be produced, and the hapless creature is instantly killed. It would probably require ten thousand of my artificial batteries to effect the same object, as the creature is killed instanter on receiving the shock. As much, however, as my battery is inferior to that of the electric fish, so is man superior to the same animal. Man is endowed with a power of mind competent to appreciate the force of matter, and is thus enabled to make the battery. The eel can but use the specific apparatus which nature has bestowed upon it.”
Some observations upon the electric current around the gymnotus, and notes of experiments with this and other electric fish, will be found in Things not generally Known, p. 199.