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.

They comprise the gases—oxygen, hydrogen, nitrogen, and chlorine, and such substances as sulphur, carbon, phosphorus and iodine. To the latter class also belongs a peculiar element called fluorine, which, when combined with hydrogen, destroys glass. It is the only liquid known which cannot be contained in a glassen or earthenware vessel, and when used for experimental purposes must be kept in a leaden bottle.

Of course it will be understood that the above is not a complete list by any means, but is sufficient to give a clear idea of the difference between the two classes. The metals generally speaking are of a more or less sparkling, lustrous appearance. The metals, too, are good conductors of heat and electricity, and generally heavy. These characteristics are almost entirely wanting in the non-metals. We shall now give some tricks with the metals.