Effect of Compression.
Take a wooden reel and hollow out either the top or bottom, beginning at the hole in the center and working towards the edge. In the hollow place a ball. Apply to the other end the indiarubber tube which conducts the forced air, and the ball will be lifted up (see fig.).
To Cover Iron with Copper.
If you are about to perform a conjuring trick, you will, of course take great care that your apparatus is ready. Therefore, clean your piece of iron or steel from dirt. Dip a piece of polished iron—the blade of your knife, for instance—into a solution, either of nitrate or sulphate of copper, when it will assume the appearance of a piece of pure copper.
The Elements.
Before entering into the next series of experiments the young chemist must know that all the substances of which the world and everything in it are made up—i.e., the elements are arranged in two classes, the metals and the non-metals. The former are by far the more numerous, altogether numbering more than fifty. Among the better known are such well known substances as iron, mercury, copper, tin, potassium, antimony, strontium, and nickel. The non-metals are more widely distributed and together made up of the bulk of the universe.