This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
This is prepared by receiving into a certain measure of water, contained in a bottle, the gaseous ammonia proceeding from a mixture of fixed quantities of muriate of ammonia and lime, exposed to heat. The muriatic acid reacts with the lime, forming chloride of calcium and water; and the ammonia passes over with the aqueous vapour, and is condensed in the water of the bottle. The solution thus obtained being too strong, distilled water is added so as to render its sp. gr. 0.960. it may also be prepared from the stronger water of ammonia (see page 755) by simply diluting it with distilled water as above.
This preparation, when pure, is a solution of ammonia in water, but is apt to contain some carbonate, the presence of which may be known by the production of a precipitate on the addition of lime-water. it is colourless, of a very pungent smell, and an exceedingly acrid, burning, alkaline taste; but it could not be borne in the mouth without dilution.
We are to consider the preparation here simply as a rubefacient. Applied undiluted to the skin, it produces inflammation with redness, which, with a sufficient continuance of the application, would advance to vesication, and even to gangrene. The solution is, therefore, scarcely ever used in this state; but generally in combination with fixed oil, which not only dilutes it, but modifies its stimulant properties, by combining with it to form a soap.
Liniment of Ammonia, or Volatile Liniment (Linimentum Ammonio, U. S., Br.), is the form in which ammonia is probably most frequently used with a view to its rubefacient effect. it is prepared by simply shaking together, in a bottle, a mixture of one fluidounce of solution of ammonia and two of olive oil. in the British preparation the proportion is one measure to three; but their solution of ammonia is somewhat stronger than the U. S. water. A thick, yellowish-white liquid is thus obtained, which consists of a soap of ammonia, partly dissolved and partly suspended in water. it is much used in rheumatic pains, inflammation of the throat, and catarrhal affections, especially in children. Should it occasion too much inflammation, it may be further diluted with oil. it may be applied as a lotion, or by moistening with it a piece of flannel to be placed in contact with the skin, and covered so as to prevent, as much as may be, the escape of the gas, which may prove irritant if inhaled.