The Meta-Encyclopedia

Ammonia

3 of the 6 encyclopedias on this shelf carry an entry for Ammonia. All 3 are reproduced below, so you can see where they agree and where they differ.

Collier's New Encyclopedia (1921)

a substance consisting of NH3. Molecular weight, 17. Sp. gr. 8.5, compared with H; compared with air (1), its sp. gr. is 0.59. It is a colorless, pungent gas, with a strong alkaline reaction. The liquor ammoniæ of the pharmacopœia has a specific gravity of 0.959, and a fluid drachm contains 5.2 grains of NH3. Ammonia is obtained by the dry distillation of animal or vegetable matter containing nitrogen; horns, hoofs, etc., produce large ge quantities; hence its name of spirits of hartshorn. Guano consists chiefly of urate of ammonia. But ammonia is now obtained from the liquor of gasworks, coal containing about 2 per cent. of nitrogen. Ammonia is formed by the action of nascent hydrogen on dilute acetic acid. Ammonia gas is prepared in the laboratory by heating together one part of NH.Cl with two parts by weight of quicklime, and is collected over mercury. NHs is decomposed into N and Hs by passing it through a red-hot tube, or by sending electric sparks through it; the resulting gases occupy twice the volume of the ammonia gas. It is used in medicine as an antacid and stimulant; it also increases the secretions. Externally, it is employed as a rubefacient and vesicant. Ammonia liniment consists of one part of solution of ammonia to three parts of olive oil. Ammonia is used as an antidote in cases of poisoning by prussic acid, tobacco, and other sedative drugs.

Aiton's Encyclopedia (1910)

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

The Encyclopedia of Founding (1892)

A colorless irrespirable gas, of an extremely pungent and caustic taste, lighter than air (sp. gr. 0.59). It exists in very minute quantities in the atmosphere, rain-water, fog, and dew. Ammonia is the only known compound of nitrogen and hydrogen; it is a constant product of the decomposition of organic substances which contain nitrogen. It is produced from the destructive distillation of horns and hoofs, but the liquor of the gas-works furnishes the chief source of commercial ammonia. Being a gas it is called volatile alkali to distinguish it from those which are fixed, or solid. Owing to the fact that it was derived from the horns of harts, it is commonly called spirits of hartshorn. See ALKALI.

What Has Changed in the Last Century

All three accounts describe ammonia as something you collect: distilled from horns and hoofs, or skimmed off the liquor of gasworks at Aiton's rate of "about five pounds" per ton of coal. Within a few years of those words, Fritz Haber's 1909 demonstration and Carl Bosch's Oppau plant of 1913 made it instead from the nitrogen of the air, and world output now runs to roughly 180 million tonnes a year, about four-fifths of it going to fertilizer. Collier's medical uses — ammonia as an antacid, a stimulant, a blister-raising vesicant, an antidote to prussic-acid poisoning — have all been abandoned. Two smaller corrections: the 1892 claim that ammonia is "the only known compound of nitrogen and hydrogen" was already outdated, hydrazine having been prepared by Theodor Curtius in the 1880s, while Aiton's refrigeration use survives, ammonia still being the standard refrigerant in large industrial cold stores.

Written for this edition, 2026.