ELECTRICAL PHENOMENA.
(From the Treatise on Electricity—in the Library of Useful Knowledge.)
The colours produced by the electric explosion of metals have been applied to impress letters or ornamental devices on silk and on paper. For this purpose Mr. Singer directs that the outline of the required figure should be first traced on thick drawing paper, and afterwards cut out in the manner of stencil plates. The drawing paper is then placed on the silk or paper intended to be marked; a leaf of gold is laid upon it, and a card over that; the whole is then placed in a press or under a weight, and a charge from a battery sent through the gold leaf. The stain is confined by the interposition of the drawing paper to the limit of the design, and in this way a profile, a flower, or any other outline figure may be very neatly impressed.
Most combustible bodies are capable of being inflamed by electricity, but more especially if it be made to strike against them in the form of a spark or shock obtained by an interrupted circuit, as by the interposition of a stratum of air. In this way may alcohol, ether, camphor, powdered resin, phosphorus, or gunpowder be set fire to. The inflammation of oil of turpentine will be promoted by strewing upon it fine particles of brass filings. If the spirit of wine be not highly rectified, it will generally be necessary previously to warm it, and the same precaution must be taken with other fluids, as oil and pitch; but it is not required with ether, which usually inflames very readily. But on the other hand, it is to be remarked that the temperature of the body which communicates the spark appears to have no sensible influence on the heat produced by it. Thus the sparks taken from a piece of ice are as capable of inflaming bodies as those from a piece of red-hot iron. Nor is the heating power of electricity in the smallest degree diminished by its being conducted through any number of freezing mixtures which are rapidly absorbing heat from surrounding bodies.