Qualities. Form: white, semi-transparent masses, of a striated or crystalline aspect, which, on exposure to air effloresce; Odour, pungent and peculiar; Taste, acrid but cooling. Chemical Composition. It will be found to vary materially in its composition according to the temperature employed for its preparation; the quantity of alkali varying from 20 to 50 per cent. Mr. Phillips considers the Sub-carbonate of ammonia to be a Sesque-carbonate, composed of 3 atoms of carbonic acid, 2 atoms of ammonia, and 2 of water; or that it is a definite compound of Carbonate and Bi-carbonate, one atom of each, with two atoms of water; one hundred parts, by experiment, consist, of 54·2 carb: acid, 29·3 Ammonia, and 16·5 water; if we consider it as a Sesque-carbonate, its constitution, according to Dr. Wollaston’s scale, will be 55·72 Carbonic Acid, 29 Ammonia, 15·28 water. Solubility. According to Duncan it is soluble in twice its weight of cold water; Mr. Phillips states four times; the mean of these will be found nearly correct. Its solubility however is increased by increase of temperature, but when dissolved in boiling water it effervesces, and undergoes a partial decomposition; it is quite insoluble in alcohol, and hence on the addition of spirit to a strong solution, a dense coagulum is produced. Incompatible Substances. It is decomposed by acids, fixed alkalies, and their sub-carbonates, lime, solution of muriate of lime, magnesia, alum, super-tartrate of potass, and all the acidulous salts, sulphate of magnesia, acetate, sub-muriate, and oxy-muriate of mercury, acetate, and sub-acetate of lead, and the sulphates of iron and zinc. If it be added to decoctions and infusions they must be previously cooled. Forms of Exhibition. Since by exposure to air its virtues are impaired, it ought not to be kept in powdered mixtures; in the form of pill it is preserved much longer, especially if it be combined with some vegetable extract. Uses. It is stimulant, antispasmodic, diaphoretic, powerfully antacid, exceeding in this respect the fixed alkalies, and in large doses it is emetic. It is highly useful as a stimulant in those gastric affections which supervene habits of irregularity and debauchery; combined with opium it affords a powerful resource in protracted diarrhœa attended with debility of the alimentary canal: and in cases of muscular atony so frequently witnessed, as the sequela of chronic rheumatism, ammonia, in large doses, offers the best remedy; I have moreover witnessed the beneficial effects of this remedy in hoarseness depending upon relaxed states of the throat. In typhus fever it has been particularly recommended by Huxham, Pringle, and many other physicians, and some have considered it superior to any other stimulant upon such occasions. It is also useful in syncope and hysteria, in the form of smelling salts;[[366]] with respect to its application for making saline draughts, see Acid: Citricum: Dose, grs v to ℈j: to produce emesis ʒss. See Form. 48, 49, 83, 152. Officinal Preparations. Liquor Ammoniæ sub-carbonatis, L. Liquor Ammoniæ acetatis (I) L.E.D. Liniment: Ammoniæ Sub-carbonatis. L. Cuprum Ammoniatum, (I) L.E.D. Adulterations. This salt ought to be entirely volatilized by heat; if any thing remain it may be considered impure; it ought also to be free from all fetor; should this not be the case it may be corrected by subliming it in conjunction with powdered charcoal; there is at present a large quantity of this impure article in the market, which has been manufactured from the residue sold by the gas light companies.[[367]] When long exposed to the air, it becomes opaque and friable, and the excess of ammonia, upon which its odour depends, escapes, carbonic acid is absorbed, and an inodorous bi-carbonate remains, consisting of carbonic acid 55·70, Ammonia 21·52, and water 22·76, or 2 atoms of carbonic acid, 1 atom of ammonia, and 2 atoms of water.
AMMONIÆ MURIAS. L.E. Sal Ammoniacum. D.
vulgo Sal Ammoniac.
Qualities. Form, dense striated concavo-convex cakes which are persistent in the air, or crystallized conical masses; in this latter form it generally contains other salts, especially muriate of lime, which render it deliquescent. Taste, bitter, acrid, and cool. Chemical Composition. In consequence of the present unsettled opinions respecting the nature of muriatic acid and ammonia, and the changes which they undergo by combination with each other, the composition of this salt is involved in some obscurity. According to Dr. Thomson, it consists of equal volumes of muriatic acid gas and ammoniacal gas, although he has subsequently observed that from the peculiar properties of the substance, it may be a compound of Chlorine and Ammonium (the hypothetical base of ammonia.) Unlike all the other ammoniacal salts, it does not undergo decomposition by heat. Solubility, f℥j of water at 66° dissolves about two drachms and a half; at 212° it dissolves its own weight; it is also soluble in 4½ parts of alcohol; its solution in water is accompanied by considerable reduction of temperature. Incompatible Substances. The sulphuric and nitric acids unite with the ammonia, and disengage the muriatic acid, whilst ammonia is disengaged by the action of potass and its carbonate, carbonate of soda, lime, magnesia, &c. which combine with its muriatic acid; with oxy-muriate of mercury it combines and increases its solubility, see Hydrarg: Oxy-murias. When united with acetate of lead, it decomposes it, and a muriate of lead is precipitated. It is obvious also that nitrate of silver, and all the metallic salts whose bases form insoluble compounds with muriatic acid, are incompatible with it. Uses. Rarely employed as an internal remedy, externally it is employed in lotions, either for the cold produced during its solution, in which case it should be applied as soon as the salt is dissolved, or for the stimulus of the salt, on which principle it acts as a powerful discutient in indolent tumours (Form. 146.) It is also an ingredient in a very useful plaster, in which it undergoes chemical decomposition; this plaster consists of Soap ℥j, lead plaster, ʒij, liquified together, to which, when nearly cold, are added of muriate of ammonia finely powdered ʒss. The alkali of the soap enters into combination with the muriatic acid of the muriate of ammonia, and forms thereby muriate of potass, or soda, and ammoniacal gas (on which the virtue of the plaster depends) is slowly but abundantly liberated, acting as a powerful stimulant and rubefacient: it should be applied immediately after it is formed, and be renewed every twenty-four hours, otherwise the intention is lost; (Pharmacopœia Chirurgica.) I have often applied this plaster with evident advantage to the chest in pulmonary affections, and I wish to recommend it to the attention of practitioners. It is very useful also in that rheumatic affection of the muscles of the chest, which is so frequently met with in persons in advanced life; during the last winter I was consulted in two cases where the distress after exercise was so considerable as to resemble angina pectoris. Officinal Preparations. Ammoniæ Sub-carbonas (I). L.E.D. Liquor: Ammoniæ (K). L. Aqua Ammoniæ. E.D. Hydrarg: præcip: alb: (I). L. Alcohol Ammoniatum, (I). E.D. Ferrum Ammoniat: (G). L.E.D. Adulterations. This salt, if pure, may be entirely volatilized by a low heat; the sulphate of ammonia however, as it is also volatile, cannot be discovered except by the muriate of baryta, which will indicate its presence by a copious precipitate.
AMYGDALÆ DULCES. {Varieties of “Amygdalus Communis.”
AMYGDALÆ AMARÆ. {Sweet and Bitter Almonds.
Qualities. The sweet almond is inodorous, and has a sweet, bland taste; the bitter almond,[[368]] when triturated with water, has the odour of the peach, and a pleasant bitter flavour. Chemical Composition. Boullay has lately confirmed the analogy which Proust had stated to exist between the emulsion of sweet almonds and human milk, viz. the former consists of sweet oil 54, albumen 24, sugar 6, gum 3, with traces of acetic acid; the indigestible property of the almond depends upon its albuminous matter. The bitter almond, in addition to those constituents, contains hydro-cyanic acid, (Prussic acid,) in union with a peculiar volatile oil, upon which its narcotic properties depend; but this deleterious element is so modified by the natural state of combination in which it exists with sweet oil and albumen, that they may be eaten without inconvenience. The bitter almond has long been regarded as an antidote to drunkenness; Plutarch states it as a fact on the authority of his physician Claudius. Other bitters were however supposed to possess similar powers in this respect, hence the Poculum Absinthiatum to which we have before alluded. See page 79. Both sorts of almonds yield by expression a large quantity of fixed oil, which is perfectly mild. See Oleum Amygdal. The water distilled from the bitter almond, when strongly impregnated, has been found to exert a deleterious action on the human body, and to prove fatal to many animals. Solubility. By trituration with water a milky mixture is produced, (an emulsion), for which purpose the sweet almonds should be previously freed from their cuticle, (blanched), and this ought to be performed by infusing them in tepid water; for when hot it separates a portion of their oil, as is evident from their being thus rendered yellow, and the emulsion is therefore more liable to ferment, and be decomposed. ℥ij of almonds saturate about f℥vj of water; since however this extemporaneous preparation is tedious and inconvenient, the London Pharmacopœia very judiciously directs a confection to be ready prepared, ʒj of which, when triturated with f℥j of water, immediately forms an elegant emulsion. See Mistura Amygdal. Almonds form a useful intermedium for suspending in water many substances which are of themselves not miscible with it, as camphor, and several of the gum-resins; they also assist in the pulverization of refractory substances, as Ipecacuan, &c. Officinal Preparations. Confectio Amygdalarum. L. Emulsio Camphoræ (M.) E. Emulsio Acaciæ Arab: E. D.
Amygdalæ Placenta. Almond Cake is the substance left after the expression of the oil, which when ground forms Almond Powder, so generally used for washing the hands.[[369]]
Oil of Bitter Almonds. For obtaining this oil, the expressed cake is submitted to distillation, when a highly volatile, pungent, oil passes over. See Oleum Amygdalæ Amaræ.
AMYLUM. L.E.D. Starch. (Triticum Hybernum Amylum.[[370]])