Ammonia

a colorless, pungent gas composed of one atom of nitrogen to three of hydrogen. It is a light gas, about half as heavy as ordinary air. It flies up one's nose with an acrid, intense effect, bringing tears into the eyes. Ammonia is absorbed readily by water, in which form, of greater or less strength, it is usually sold, and is a familiar household article. The name is thought to have been derived from the temple of Ammon in Egypt, in the neighborhood of which, it is stated, ammonia was prepared first from the dung of camels. Ammonia was prepared formerly in commercial quantities by heating the antlers of deer in a retort, whence the spirits of hartshorn, used as the basis of smelling salts for headache. It is now obtained chiefly as a by-product in the preparation of illuminating gas from coal. About five pounds of ammonia are obtained from one ton of coal. At a temperature of --29 degree Fahrenheit ammonia liquefies. As it absorbs an immense amount of heat in vaporizing, it is much used in making artificial ice and in creating the degree of cold required for cold-storage. Large quantities of ammonia are required in dyeing establishments and in cotton factories. It is indispensable in the printing of calico. See Ice; Cold Storage