The strong alkalies, such as potash and soda, also decompose ether slightly after a time, but not immediately. Exposed to air and light, ether is oxidized and acquires a peculiar odor.
Ether dissolves fatty and resinous substances readily, but inorganic salts are mostly insoluble in this fluid. Hence it is that iodide of potassium and other substances dissolved in alcohol are precipitated to a certain extent by the addition of ether.
Fluoride of Potassium.
Symbol, KF. Atomic weight, 59.
Preparation.—Fluoride of potassium is formed by saturating hydrofluoric acid with potash, and evaporating to dryness in a platinum vessel. Hydrofluoric acid contains fluorine combined with hydrogen; it is a powerfully acid and corrosive liquid, formed by decomposing flour spar, which is a fluoride of calcium, with strong sulphuric acid; the action which takes place being precisely analogous to that involved in the preparation of hydrochloric acid.
Properties.—A deliquescent salt, occurring in small and imperfect crystals. Very soluble in water: the solution acting upon glass in the same manner as hydrofluoric acid.
Formic Acid.
Symbol, C{2}HO{3}. Atomic weight, 37.
This substance was originally discovered in the red ant (Formica rufa), but it is prepared on a large scale by distilling starch with binoxide of manganese and sulphuric acid.
Properties.—The strength of commercial formic acid is uncertain, but it is always more or less dilute. The strongest acid, as obtained by distilling formiate of soda with sulphuric acid, is a fuming liquid with a pungent odor, and containing only one atom of water: it inflames the skin in the same manner as the sting of the ant.