The limits of the present Work allow only of a simple sketch of the subjects which it is proposed to treat in this Chapter. Our attention therefore must be confined to an explanation of certain points which are alluded to in the First Part of the Work, and without a proper understanding of which it will be impossible for the reader to make progress. The following division may be adopted:--The more important Elementary Bodies, with their symbols and atomic weights; the Compounds formed by their union; the class of Salts; illustrations of the nature of Chemical Affinity; Chemical Nomenclature; Symbolic Notation; the laws of Combination; the Atomic Theory; the Chemistry of Organic Bodies. THE CHEMICAL ELEMENTS, WITH THEIR SYMBOLS AND ATOMIC WEIGHTS. The class of elementary bodies embraces all those substances which cannot, in the present state of our knowledge, be resolved into simpler forms of matter. The chemical elements are divided into "metallic" and "non-metallic," according to the possession of certain general characters. The following are some of the principal non-metallic elements, with the symbols employed to designate them, and their atomic weights:[55]-- Symbol. Atomic Wt. Gases. { Oxygen O 8 { Hydrogen H 1 { Nitrogen N 14 { Chlorine Cl 36 Solids. { Iodine I 126 { Carbon C 6 { Sulphur S 16 { Phosphorus P 32 Liquid. Bromine Br 78 Unknown. Fluorine F 19 The metallic elements are more numerous. The following list includes only those which are commonly known:-- Symbol. Atomic Wt. Metals of the { Potassium K 40 Alkalies. { Sodium Na 24 Metals of the { Barium Ba 69 Alkaline { Calcium Ca 20 Earths { Magnesium Mg 12 Metals { Iron Fe 28 Proper. { Zinc Zn 32 { Cadmium Cd 56 { Copper Cu 32 { Lead Pb 104 { Tin Sn 59 { Arsenic As 75 { Antimony Sb 129 Nobel { Mercury Hg 202 Metals. { Silver Ag 108 { Gold Au 197 { Platinum Pt 99 [55] The atomic weights, with the exception of that of Gold, are taken from the last edition of Brande's 'Manual of Chemistry.'