Sulphurous Acid
an acid formed by the union of an equivalent of sulphur with two of oxygen in a variety of ways, the most familiar being its production during the combustion of sulphur in the open air or in oxygen. The gas produced is endowed with the properties of a weak acid, and is the sole product of the combustion, provided the air or oxygen be perfectly dry. It has a pungent, suffocating odor, and when in a concentrated form cannot be breathed with impunity. It is not inflammable, and extinguishes burning bodies. It dissolves freely in water, which takes up between 40 and 50 times its bulk of the gas. The solution has the smell and taste of the gas itself, and becomes gradually converted into sulphuric acid from absorbing oxygen from the air. It is widely used in the manufacture of disinfectants and in fumigation.