Compound bodies are made up of two or more elementary substances chemically combined with each other; thus sulphur, copper, lead, are elementary bodies; out of each of these nothing different from sulphur, copper, lead, can be obtained; whereas when two of these bodies are heated together, a compound is formed from which both of the original elementary constituents can at any time be obtained. Water is a compound body--it can be split up into two elementary gases, hydrogen and oxygen; common salt, again, is a compound of a gas (chlorine) with a metal (sodium); and limestone, clay, sugar, and wax may serve as examples of compound bodies; whilst phosphorus, charcoal, iron, mercury, and gold may be mentioned as belonging to the class of simple substances. As to physical properties of gases--they have weight, volume, diffusion, density, etc. Theologians insist that there is a God, a God that was first introduced to us by a man with the name of Abraham, advertised by Moses, and has been palmed off upon the masses as a something exceedingly wonderful. A multitude of men who find it to their interest to advocate his pretended claims, are still doing their utmost to sustain their God. We are trying to discover where he is to be found, whether he is a local or a universal God, what he is composed of, whether he resides on earth permanently or transiently, whether he controls the entire solar system or more systems, whether he occasionally takes a trip to other planets; and if he has created everything we want to find out how he has created it. For that reason we have to search, taking a glimpse among the stars, in the earth, atmosphere, etc. Since geology does not respond favorably, we are trying to discover what this earth is composed of. The elementary bodies at present recognized amount to sixty-four in number. Of these about fifty belong to the class called metals. Several of them are of recent discovery, and as yet very imperfectly known. The distinction between metals and certain non-metallic substances or metalloids, although very convenient for purposes of description, is entirely arbitrary, since the classes graduate into each other in the most indefinite manner. The following is a complete list of the elementary substances known, giving their names, symbols, and combining weight: Symbols. METALLOIDS. Combining Weight. Elements of life: of primary importance. O Oxygen [1] II 16 H Hydrogen I 1 N Nitrogen V 14 C Carbon IV 12 Elements of secondary importance.