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symbol, chemical and elements

SYMBOLS, Chemical, letters or symbols used in chemistry to designate the various chemical elements. They are merely the first letters of the names of these elements (not in every case of their English name); or when the names of two or more elements begin with the same letter, two letters are used as the symbol, one of which is always the first letter of the name of the element: Generally speak ing the letters comprising the symbol are taken from the English name of the element; but in some instances, specially in the cases of metals which have been long known, the symbols are derived from the Latin names: thus we have Hp, symbol for mercury, from the Latin Hydrargyrum; Fe. from the Latin Ferrum, for iron; and so on. In a few cases the symbols are deduced from the old German names: thus K. the symbol for potassium, is the first letter of the old German word Kalium. and Na, the symbol for sodium, is from the German Natrium. However derived, whether from English, German, Latin or French, the symbols of the chemical elements are universally the same. For a considerable time French chemists employed the symbol As to represent nitrogen, from the name Azote, which was given to this element in reference to the fact that it alone could not support life (Greek, a, privative, and ape, life); but this symbol is now almost en tirely superseded by the letter N. The symbols

of chemical compounds are constructed by plac ing together the symbols of their constituent elements, a number being attached to each signifying how many atoms of the element enter Into the composition of the amount of the compound expressed by the entire symbol. For it must be understood that chemical symbols have a quantitative as well as a qualitative meaning. When a chemist meets in a chemical treatise with the symbol 0 he knows that this signifies not only oxygen but a certain definite amount by weig•ht of oxygen, 0 always means 16 parts by weight of oxygen, so Fe means 56 parts by weight of iron; and so also the com pound symbol Fess% means (56 X 2) + (16 X 3) = 160 parts by weight of oxide of iron. For a further account of the uses and modes of formation of chemical symbols see the article CHEMISTRY.