Jöns Jacob Berzelius (1779-1848)

Essay on the Cause of Chemical Proportions, and on Some Circumstances Relating to Them: Together with a Short and Easy Method of Expressing Them.

III. On the Chemical Signs, and the Method of Employing them to Express Chemical Proportions.

The chemical signs ought to be letters, for the greater facility of writing, and not to disfigure a printed book. Though this last circumstance may not appear of any great importance, it ought to be avoided whenever it can be done. I shall take, therefore, for the chemical sign, the initial letter of the Latin name of each elementary substance: but as several have the same initial letter, I shall distinguish them in the following manner:-- 1. In the class which I call metalloids, I shall employ the initial letter only, even when this letter is common to the metalloid and some metal. 2. In the class of metals, I shall distinguish those that have the same initials with another metal, or a metalloid, by writing the first two letters of the word. 3. If the first two letters be common to two metals, I shall, in that case, add to the initial letter the first consonant which they have not in common: for example, S = sulphur, Si = silicium, St = stibium (antimony)[2], Sn = stannum (tin), C = carbonicum, Co = cobaltum (cobalt), Cu = cuprum (copper), O = oxygen, Os = osmium, &c.

The chemical sign expresses always one volume of the substance. When it is necessary to indicate several volumes, it is done by adding the number of volumes: for example, the oxidum cuprosum (protoxide of copper) is composed of a volume of oxygen and a volume of metal; therefore its sign is Cu + O. The oxidum cupricum (peroxide of copper) is composed of 1 volume of metal and 2 volumes of oxygen; therefore its sign is Cu + 2O. In like manner, the sign for sulphuric acid is S + 3O; for carbonic acid, C + 2O; for water 2H + O, &c.

When we express a compound volume of the first order, we throw away the +, and place the number of volumes above the letter[3]: for example, CuO + SO³ = sulphate of copper, CuO² + 2SO³ = persulphate of copper. These formulas have the advantage, that if we take away the oxygen, we see at once the ratio between the combustible radicals. As to the volumes of the second order, it is but rarely of any advantage to express them by formulas as one volume; but if we wish to express them in that way, we may do it by using the parenthesis, as is done in algebraic formulas: for example, alum is composed of 3 volumes of sulphate of aluminia and 1 volume of sulphate of potash. Its symbol is 3(AlO² + 2SO³) + (Po² + 2SO³). As to the organic volumes it is at present very uncertain how far figures can be successfully employed to express their composition. We shall have occasion only in the following pages to express the volume of ammonia. It is 6H + N + O or H⁶NO.

Comparative Table of the Specific Weights of Elementary Bodies[4]

[2][The abbreviations employed in this lengthy paper are not entirely consistent throughout. These include antimony (St or Sb), columbium (now known as niobium, Cb or Cl), lead (P or Pb), manganese (Mn or Ma), mercury (Hy or Hg), rhodium (R or Rh), tin (Sn or St), and tungsten (W or Tn). The symbols and/or names of several other elements differ from present usage. These include chromium (Ch rather than Cr), glucinum (Gl rather than beryllium, Be), magnesium (Ms rather than Mg), muriatic radicle (M rather than chlorine, Cl), potassium (Po rather than K for Kalium), and sodium (So rather than Na for natrium). --CJG]

[3][When he said above, he meant directly above, not above and to the right, as I have rendered the formulas here. --CJG]

[4][The table appears to be arranged in order of polarity from electronegative to electropositive as Berzelius used the terms in his dualistic theory of bonding. --CJG]