Alkali

Alkali, a name originally given to the ashes of seaweeds; but now applied to other substances which possess the properties which are characteristic of seaweed ash, and including the compounds of the five so-called Alkali metals, Potassium, Sodium, Lithium, Rubidium, and Caesium, and the metallic radicle Ammonium, with Hydrogen and Oxygen. Alkalis are marked by great solubility in water, the power of neutralising and being neutralised by acids to form salts, the property of reddening blue litmus paper, of precipitating the heavier metals from their solutions as oxides, and finally, by their general corrosive action on organic bodies. The determination of the amount of Alkali in a given substance is termed Alkalimetry, and is precisely analogous in method to that of Acidimetry.