Acacia Senegal, Willdenow, and other African species.
The dried, gummy exudation.
Habitat. E. and W. Africa, Senegal, Kordofan, Egypt, Abyssinia, India, Nubia, Upper Nile.
Syn. Acac., Gum Arabic, Gum Senegal, Egyptian Thorn, Indian Gum Tree, Babla(c)h Pods, Acacia bambolah, Gummi Africanum or Mimosae; Br. Acaciae Gummi, Gum Acacia; Fr. Gomme arabique du Senegal; Ger. Gummi arabicum, Arabisches Gummi.
A-ca'cia. L. fr. Gr.
a thorny Egyptian tree, fr.
a point - i. e., tree studded with thorns.
Sen'e-gal. L. belonging to Senegal, a country and river in W. Africa - i. e., the plant's original and present habitat.
Arabic - misnomer, as Arabia produces little and exports none.
Plant. - Shrubby tree, 6 M. (20°) high; stem tortuous with terete branches, nodes with 3 short, black-tipped spines subtending the leaves; bark smooth, grayish-brown; leaves alternate, bipinnate, paripinnate, 2.5-4 Cm. (1-1 3/5') long; pinnae 3-5 pairs; leaflets sessile, 10-20 pairs, grayish-green, 4 Mm. (1/6') long; flowers yellow, spikes; fruit (pod), loment, compressed, smooth, pale, 7.5-10 Cm. (3-4') long, 18 Mm. (3/4') broad, 2-6-seeded. Gum (acacia), in ovoid, spheroidal tears, broken, angular fragments, 2-30 Mm. (1/12-1 1/2') broad, whitish, yellowish, amber-colored, translucent, brittle; fracture glasslike, sometimes iridescent; nearly inodorous; taste insipid, mucilaginous; insoluble in alcohol, slowly and almost completely soluble in water (2), forming mucilaginous liquid of slight, characteristic odor and acid reaction. Tests: 1. Aqueous solution (1 in 10) 10 Ml. (Cc.), + basic lead acetate T. S. (.1), or + ferric chloride T. S. (.1), or + concentrated solution of sodium borate (.1), or + alcohol - gelatinous precipitate. 2. With iodine T. S. - not blue (lim. of starch), nor red (abs. of dextrin); does not reduce alkaline cupric tartrate V. S. 3.
Fig. 174. - Acacia Senegal.
Precipitate with ferric chloride T. S. - neither black nor brownish-black (abs. of tannin). Powder, whitish, few or no starch grains nor vegetable tissue fragments; should contain not more than 15 p. c. of moisture, and not more than 1 p. c. should be insoluble in water (lim. of plant tissues, sand, dirt). Dose, ad libitum.
Adulterations. - Gum: Inferior, dark colored, opaque and insoluble gums, bdellium, rock salt, ligneous and earthy substances, dextrin in lumps; Powder: Flour, rice flour, starch, dextrin - all recognized by solubility, viscosity, the microscope, and iodine test. The gum from quince seed, flaxseed, Irish moss, etc., often used as a substitute.
Commercial. - Plants grow associated with little other vegetation sandy soil, deserts, forming entire forests. Gum, a degenerative product, the result of "gummosis" - transformation of cell contents (cellulose) in the cambium, cortex, and adjacent parenchyma, a process favored in dry hot seasons and unhealthy trees - exudes as a thick juice through fissures caused by dry winds after the rainy season, or artificial incisions, and sooner or later, whereby depends color, hardens on the bark similar to our cherry, apple, or plum gum. It is collected Oct. Dec., some in March, by the Moors and negroes, who in caravans enter the acacia forests and gather it in leather sacks, detaching adherent lumps with wooden axes and picking up fallen pieces from the ground. It enters market in bags, boxes, casks, skins, mostly from Egypt, via Cairo, Alexandria, Trieste, where it is received as unassorted acacia, "acacia in sorts" - the aggregated product of various species, assorted into "first picked," "second picked," etc., down to sorts (unworthy of assorting) - there being recognized at Trieste thirty-two grades. Acacia is known by the natives as Verek (Senegal) or Hashabi (E. Africa), the best being white, opaque, and chiefly from A. Senegal (Ve'rek) and A. arabica (vera), which grow promiscuously with other species and contribute the several varieties: 1, Turkey (Egyptian), which includes (a) Kardofan (A. Senegal), from west of White Nile, once constituting the bulk of the superior gum, (b) Sennaar (A. fis'tula, A. stenocar'pa), from east of White Nile, inferior, mucilage sours'quickly, (c) Suakin (Talca - A. stenocarpa, A. Sr'yal), from near Red Sea, mixture of white and brown pieces, very brittle, usually semi-pulverulent, only soluble with alkali; 2, Senegal (A. Senegal), from north of Senegal River, W. Africa, being controlled by France and shipped to Bordeaux; larger than Turkey gum, some nodules the size of a pigeon egg, less brittle, more yellow or reddish, with fewer cracks and more conchoidal fracture, not amber-yellow when heated with potassium hydroxide, as are Turkey gum and dextrin solutions; 3, Barbary (Morocco, Mogador - A. nilot'ica, A. arabica), collected July-August, consisting of two kinds that enter Mogador, one from Morocco (resembling Turkey), the other from Timbuctoo (resembling Senegal), both in more or less brownish, roundish tears, brittle, soluble in water; 4, India (A. arabica, +), from Somali districts, E. Africa, conveyed by Arab vessels to Bombay; resembles somewhat Turkey and Senegal gums, however, much mixed and often containing Bassora gum or allied substances (insoluble, swelling and softening with water into viscid mass), also resinous products resembling turpentines; deprived of these the variety is well suited for general use.
Gums are produced also by other Acacia species in Morocco, Cape Colony, Australia (Wattle gum), Brazil (Para, Angico gum), etc.; Mez-quite gum (Proso'pis juliflo'ra), Texas, California, New Mexico, Chile, resembles acacia, but is yellow, brown, and not precipitated by lead sultacetate, ferric chloride, borax; also considerable gum from plants of different genera and family, darker color but resembling the official.
Powdered acacia occurs in two forms: 1, Granulated (sanded), to produce which the gum needs to lose only 2 p. c. of moisture; 2, Finely powdered (dusted), in which the gum must lose 10 p. c. of moisture to produce a sufficiently fine powder - a process that renders it more lumpy and less soluble in water.
Constituents. - Arabic acid, C12H22O11, combined with Ca, Mg, K - arabates; sugar (trace), moisture 14 p. c., ash 3-4 p. c.
Arabic Acid (gummic acid, arabin). - A glucoside obtained by adding alcohol to acidified (HC1) mucilage. After drying, it swells with water, but dissolves only upon the addition of an alkali; boiled with acids yields arabinose (arabin sugar, pectinose, pectin sugar), C5H10O5, in prismatic crystals, sweet, but not directly fermentable, and possibly also galactose, granular and less sweet.
Preparations. - 1. Mucilago Acaciae. Mucilage of Acacia. (Syn., Mucil. Acac.; Fr. Mucilage de Gomme; Ger. Mucilago Gummi arabici, Gummischleim.)
Manufacture: 35 p. c. Wash acacia 35 Gm. in a tared bottle (flask) with sufficient cold water, discard washings, drain, add warm distilled water q. s. 100 Gm.; securely stopper the container, agitate until dissolved, strain. Must be made frequently and not dispensed if sour or moldy. Should be kept cool (refrigerator) in small, well-filled bottles. When cold or hot water employed alone acetic acid is formed from the acid calcium arabate, which may be neutralized by lime water (35 p. c), or retarded by alcohol (6 p. a), glycerin (10 p. c), acetanilid (.4 p. a), or chloroform (.5 p. a). Dose, ad libitum.
2. Syrupus Acacia. Syrup of Acacia. (Syn., Syr. Acac; Fr. Sirop de Gomme; Ger. Syrupus Gummosus, Gummisirup.)
Manufacture: 10 p. c. Dissolve acacia 10 Gm. in distilled water 43 Ml. (Cc.), occasionally stirring, add sugar 80 Gm., heat gradually on water-bath until contained water boils, maintain temperature for 15 minutes, and stir occasionally until sugar dissolved, strain (hot), add distilled water, recently boiled, q. s. 100 Ml. (Cc.); while hot pour into small, well-rinsed, well-dried bottles, insert tightly rubber stoppers just boiled in water for 30 minutes, cap with paper; sometimes spoils in hot weather. Dose, ad libitum.
3. Emulsum Amygdalae, 1 p. c. 4. Emulsum Olei Morrhuae, 12.5 p. c. 5. Emidsum Olei Terebinthinae, 15 p. c. 6. Mistura Glycyrrhizae Composita, 3 p. c. 7. Pilulae Ferri Iodidi, 1/7 gr. (.01 Gm.). 8. Pilulae Phosphori, 1/2 gr. (.03 Gm.). 9. Pulvis Cretae Compositus, 20 p. c. 10. Trochisci Cubebae, 2 gr. (.13 Gm.).
Unoff. Preps.: Emulsions. Pills. Troches, etc.
Properties. - Demulcent, emollient, protective, nutritive. Forms often the food of Hottentots and camels. By its viscidity sheaths inflamed surfaces; as a diluent, lessens acrimony of irritating medicines.
Uses. - Coughs, laryngitis, gastritis, typhoid fever, dysentery, diarrhoea. Fine powder locally stops slight hemorrhage; thick mucilage protects burns, ulcers, etc. In pharmacy used to suspend insoluble substances in water - emulsifying oleoresins, fixed and volatile oils, for adhering pills, troches, etc.; in arts for giving lustre to fabrics, silks, thickening colors, mordants, suspending iron tannate in ink, etc. The bark of tree for dyeing, tanning, as it contains tannic and gallic acids.
Fig. 175. - Acacia arabica.