Ale and porter drink better out of a pewter or tin pot, than from glass or earthenware; because of the galvanic influence of the green copper as used to give the beer a frothy head.
Galvanic experiments may be made with the legs of a frog. A live flounder will answer nearly the same purpose. Lay the fish in a plate, upon a slip of zinc, to which is attached a piece of wire, and put a quarter dollar upon the flounder's back; then touch the quarter dollar with the wire, and at each contact strong muscular contractions will be produced.
EXPERIMENTS IN MAGNETISM.
1. We have said that the agency of the magnet can be imparted to hard metallic bodies; this may be done in a very easy way. If you pass a magnet (which may be either natural or artificial) over a sewing-needle several times from the eye to the point, the needle will acquire the principle, and attract iron filings in the same manner as a natural magnet would do. But the part of the magnet which you apply to the needle must be the north pole; and you must not pass it over the needle backward and forward, but lift it always from the point and again begin from the eye. Suppose you wish to impart the principle to a small bar of tempered steel, tie the piece to be magnetized to a poker with a piece of silk, and hold the part of the poker to which it is attached in the left hand; take hold of the tongs, a little below the middle, with the right hand, and rub the steel bar with them, moving the tongs from the bottom to the top, and keeping them steadily in a vertical position all the time. About a dozen strokes on each side will impart sufficient magnetic power to the bar to enable the operator to lift up small pieces of iron and steel with it. The lower end of the bar should be marked before it is fastened to the poker, so that the poles may be readily distinguished from each other when it is taken off; the upper end being the south pole, and the lower the north.
2. Scatter some iron filings upon a piece of paper, and hold a magnet underneath it. The instant the contact takes place, the filings will raise themselves upright, and fall down as soon as the magnet is withdrawn. The effect is singular, and indeed very amusing; the diminutive iron particles rising and falling, as if by supernatural agency.
TEST OF MAGNETIC POWER.