Gum arabic

“ Gum Arabic.—The gum called Marocco or Barbary gum, is produced from a high thorny tree called Attaleh, having leaves similar to the Arar, or Gum Sandrac tree, and the juniper. The best kind of Barbary gum is procured from the trees of Marocco, Ras-el-wed, in the province of Suse and Bled-hummer, in the province of Abda; the secondary qualities are the produce of [137] Shedma, Duquella, and other provinces; the tree grows abundantly in the Atlas mountains, and is found also in Bled-el-jerrêde. ”

“ Pate de Gomme Arabique—Arabic Paste.—Very white gum arabic two pounds, sugar two pounds, orange-flower water four ounces, the whites of twelve eggs. Pound and sift the gum, add it to the water, dissolve and evaporate it over a slow fire, stirring it constantly until it is reduced to the consistence of honey with the sugar in syrup. Whip the whites to a strong snow; add it to the paste with the orange-flower water, gradually; stir and finish as marsh-mallow paste, for which this is mostly substituted, and much used for coughs. It should be very white, light, and spongy. ”

“ Gum arabic is not often kept in the house as a medicine, but I think it eminently proper to keep it; scarcely any other medicine is so safe and harmless either in large or small doses, and few are more decidedly useful than this in some cases. Made into an emulsion and taken either alone or in combination with other medicine, or used as food, it is good in every variety of bowel complaint. A teaspoonful of the mucilage stirred into a cup of cold water and drank by the patient, may serve as medicine and drink and sustenance when he can take no other food. ”

“ They are traversed by numerous fissures, and break easily and with a vitreous fracture. The interior is often less fissured than the outer portion. At 100° C. the cracks increase, and the gum becomes extremely friable. In moist air, it slowly absorbs about 6 per cent. of water.
The finest gum arabic is perfectly clear and colourless; inferior kinds have a brownish, reddish or yellowish tint of greater or less intensity, and are more or less contaminated with accidental impurities such as bark. ”

“ Starch and artificial gums always leave the cloth somewhat harsh in “feel” unless they are treated specially, and are moreover incapable of yielding the beautifully clear and perfectly even tints resulting from the use of natural gums. Very dark colours cannot well be obtained with gum senegal or gum arabic thickenings; they come away too much in washing, the um apparently preventing them from combining fully with the fibres. ”

“ Soon after this we first met bushes of one of the peculiar plants of South Marocco, then little known, and of which we were not able to learn much by personal inspection. The Acacia gummifera of Willdenow is one of a group of allied species of which the remainder inhabit Upper Egypt and Nubia, while one, at least, is widely [100] spread throughout Eastern Africa and Arabia. The tasteless gum known as the gum-arabic of commerce is probably produced by several of these species. ”

“ The Pharmacopœia directs the use of powdered gum and of boiling water, whereas gum, in its ordinary condition or coarsely broken, and cold water make a clearer solution. Cold water is directed for the solution of the gum by the Edinburgh process, and in our present formula for “Syrup of Gum Arabic;”—if appropriate for the latter, it is quite as much so for the forming of mucilage. When the gum has been ground in a mill it appears to have been a little charred and forms a somewhat turbid solution; if powdered by hand, and rather more coarsely, its solution is clearer. ”

“ The tree Talh (Arabic) , which produces the gum arabic (Arabic) , is very common in the Ghor; but the Arabs do not take the trouble to collect the gum. Among other vegetable productions there is a species of tobacco, called Merdiny (Arabic) , which has a most disagreeable taste; but, for want of a better kind, it is cultivated in great quantity, and all the Bedouins on the borders of the Dead sea are supplied with it. The coloquintida (Arabic or Arabic) , grows wild every where in great quantities. The tree Szadder (Arabic) , which is a species of the cochineal tree, is also very common. ”

“ Glycerine and gum arabic make a very good adhesive of a fluid nature suited to mounting photographs; and although glycerine is hygroscopic by itself, such tendency to absorb moisture is checked by the reverse nature of the gum arabic; consequently an ideal fluid mucilage is produced. The proportions of the several ingredients are these:
First dissolve the gum in the water, and then stir in the glycerine, and allow all débris from the gum to deposit before using. ”

“ Vegetable gums are secretions of plants which are generally soluble in water, and which subserve various useful purposes. Gum Arabic is one of the most important of this class of vegetable productions.
Gutta-percha is an invaluable substance lately added to the list of known vegetable productions. It is obtained by cutting the bark of trees of the class called Sapotacea. Its proper name is gutta Pulo Percha, gutta meaning gum, and Pulo Percha is the island whence it is obtained. But gutta-percha is not, strictly speaking, a gum. ”

“ The white is considered the best. It was formerly used in medicine.
GUM. Syn. Gummi, L. The general term for an important class of vegetable products. Gums are more or less soluble in cold water, but insoluble in alcohol, ether, and oils. They are obtained from certain plants in amorphous masses; most of them exude spontaneously, or on puncturing the bark. The most perfect type of this class is the substance called GUM ARABIC, or GUM ACACIA. The gums are employed as demulcents in medicines, and are used as cements, and for giving stiffness and gloss to textile fabrics. ”

“ A carbohydrate, isomeric with cane sugar, contained in gum arabic, from which it is extracted as a white, amorphous substance.
2. Mucilage, especially that made of gum arabic.
ARABINOSE
Ar"a*bin*ose`, n. (Chem.)
Defn: A sugar of the composition C5H10O5, obtained from cherry gum by boiling it with dilute sulphuric acid.
ARABISM
Ar"a*bism, n. Etym: [Cf. F. Arabisme.]
Defn: An Arabic idiom peculiarly of language. Stuart.
ARABIST
Ar`a*bist, n. Etym: [Cf. F. Arabiste.]
Defn: One well versed in the Arabic language or literature; also, formerly, one who followed the Arabic system of surgery. ”

“ Suse produces more almonds and oil of olives than all the other provinces collectively. (Gum Amarad) a red gum partaking of the intermediate quality between the (tolh gum) gum arabic and the Aurwar, or Alk Soudan Senegal gum, is first found in this province. Wax is produced in great abundance; also gum euphorbium, gum sandrac, wild thyme, worm-seed, orriss root, orchillo weed, and coloquinth. Antimony, salt-petre of a superior quality, copper, and silver, are found here; the two latter in abundance about Elala, and in Shtuka. ”

“ The compound powder is a useless preparation, as the starch it contains is very liable to ferment.
Gum kuteera resembles in appearance gum tragacanth, for which the attempt has occasionally been made to substitute it. It is said to be the product of Sterculia urens, a plant of the natural order Sterculiaceae.
Cherry tree gum is an exudation from trees of the genera Prunus and Cerasus. It occurs in shiny reddish lumps, resembling the commoner kinds of gum arabic. With water, in which it is only partially soluble, it forms a thick mucilage. Sulphuric acid converts it into l-arabinose ”

“ Gum arabic ought never to be used for appliqué work, as it becomes so hard that it is impossible to get the needle through, whilst the saccharine it contains almost always causes ugly spots to appear in the stuff when it dries. ”

“ To each pint of the strained juice add of gum Arabic, 1 oz., gently evaporate to the consistence of a syrup, and add an equal weight of bruised white sugar; as soon as the whole is united, pour it out on an oiled slab, and, when cold enough, cut it into pieces. ”

“ Gum is commonly found in those articles which {62}also contain starch; and has the same chemical composition as the latter, but is much less nutritious. In the East, gum-arabic and similar substances are largely employed as food. Persons who travel by caravan across vast, sandy deserts, find such substances well adapted to their wants, since they are not perishable, and are easily packed and carried. ”

“ There is no better way of preparing this than simply to put cold water upon gum arabic, and let it stand till dissolved. If for sticking purposes, as much water as will just cover the gum will be sufficient; but, for making quickmatch, 1 ounce or 11⁄4 ounce of gum to a pint of water. If required in a hurry, put the gum into cold water, in a pipkin, or tin saucepan, set it on the fire, make it boil, and keep stirring till dissolved. When cold, bottle, and cork it. ”

“ L. E. D.—This gum is of a strong body, and does not perfectly dissolve in water. A dram will give to a pint of water the consistence of a syrup, which a whole ounce of gum Arabic is scarce sufficient to do. Hence its use for forming troches, and the like purposes, in preference to the other gums. It is used in an officinal powder, and is an ingredient in the compound powders of ceruss and amber.—Lewis's Mat. ”

“ Soak 1⁄4 pound granulated gum arabic in 1⁄2 pint water until dissolved; this is best done by standing the covered bowl in a pan of hot water on the coolest part of the stove and stirring occasionally. ”

“ Gum arabic depolarizes light in every position, unless in extremely thin chips. Cherry gum also depolarizes light, with some appearance of a neutral axis. Caoutchouc has the same property; and though it loses it when fused by heat, it recovers the same power gradually in the course of a few weeks. ”

“ The character of the vegetation changed, and we began to pass through glades of the great mimosa forest which extends from the neighbourhood of Gedaref almost to Gallabat. Here the mimosas are not bushes but trees, and it is from them that the gum-arabic is collected which gives Gedaref its highly valuable trade and its prosperity. Large quantities of the gum are exported by way of Suakim, and there is a market for it at Cairo and other towns of Lower Egypt. ”

“ A very simple imbedding agent, and one of the greatest practical value, is a strong solution of gum arabic, which, upon being dehydrated either by ordinary drying or the action of alcohol, soon acquires such a degree of hardness as to permit it (with the imbedded tissue) to be cut with ease. ”

“ To keep the insoluble portion suspended, a mucilaginous agent is employed, and those most available are gum senegal and gum arabic. An ink so prepared develops its intensity of colour only after some exposure; and after it has partly sunk into the paper it becomes oxidized there, and so mordanted into the fibre. As the first faintness of the characters is a disadvantage, it is a common practice to add some adventitious colouring matter to give immediate distinctness, and for that purpose either extract of logwood or a solution of indigo is used. ”

“ It increases the brilliancy and the durability of ultramarine, carmine, green, and in general of all delicate colours, whilst it contributes to make them spread more evenly upon the paper, ivory, &c. When mixed with gum Arabic, it thickens the colours without communicating to them a disagreeable glistering appearance; it prevents the gum from cracking, and fixes the colours so well that others may be applied over them without degradation. ”

“ It is preferable in the form of mixture, since it is very liable in the solid state to excite nausea, and, from swimming on the contents of the stomach, to occasion pain at its upper orifice. If a larger dose be required than that which water can dissolve, an additional proportion may be suspended by means of sugar, almonds, yelk of egg, or mucilage, for which purpose three times its weight of gum arabic is required. If Camphor be first dissolved by trituration in a very small portion of oil, it readily mixes with mucilage of gum arabic, and may then be conveniently blended with liquids. ”

“ Diuretic Drops.—Two ounces of sweet spirits nitre, one ounce balsam copavia, two ounces oil almonds, one ounce spirits turpentine; mix together and add one scruple champagne. Dose—a small teaspoonful given in mucilage of gum Arabic, three or four times a day. ”

“ The seeds of the tansy are often offered for sale, for worm-seed; but the more conscientious dealer sometimes treats his customers with an equal portion of the genuine and the adulterated article.
The Spanish liquorice juice of the shops is generally137 composed of the worst kind of gum arabic, called Indian or Barbary gum, and imported chiefly for the purpose of making shoe-blacking, with a small portion of the genuine juice ”

“ Starch differs but little from sugar in composition. It is easily converted into sugar by simply heating it with a little sulphuric acid, and by other means, of which I shall have to speak more fully hereafter, when I come to the cookery of vegetables. When simply heated, it is converted into dextrin or ‘British gum,’ largely used as a substitute for gum arabic. If the heat is continued a change of colour takes place; it grows darker and darker, until it blackens just as sugar does, the final result being nearly the same. ”

“ Gum arabic.―Solutions of four degrees of strength were made; one of six grains to the ounce of water (one part to 73) ; a second rather stronger, yet very thin; a third moderately thick, and a fourth so thick that it would only just drop from a pointed instrument. These were tried on fourteen leaves ; the drops being left on the discs from 24 hrs. to 44 hrs. ; generally about 30 hrs. Inflection was never thus caused. It is necessary to try pure gum arable, for a friend tried a solution bought ready prepared^and this caused the tentacles to bend ”