GUM-RESINS. 





.'. i 



purposes for which it can be u*ad if preferable to that nude with warm 

 : . which is the common method. 



(HIMI ia not very easily digested when taken alone, and will often 

 pan through the stomach nearly unchanged, if not associated with 

 aome bitter or astringent principle. Hence the advantage of some 

 bitter extractive or astringent principle, either in the grassed them- 

 elm or in other plants, such u tormentil or leaser ctntaury. int.-r 

 aperted in the pasture lands of cattle. (See Davy, 'Agricultural 

 Chemistry;' or Sinclair, 'Hortus Gramineus Woburnensis.') This 

 property, however, renders it demulcent in affections both of the 

 throat and also of the intectines, by sheathing the membrane from air 

 or the irritation of acrid secretions. Hence allowing a portion to dis- 

 solve slowly is often useful in common colds. Mucilage is also used to 

 suspend many insoluble matters in water. Its agglutinating properties 

 render it valuable in many of the arts. 



GUM RESINS are secretions of plants which are produced in the 

 greatest quantity, and most ]ierfectly elaborated, in warm countries. 

 They are obtained chiefiy from trees and shrubs of particular tribes of 

 plants, rarely from herbaceous plants, except the large herbaceous 

 I'mbtUifmr, which yield the fo-tid gum-resins. They either exude 

 spontaneously, or are procured by incisions of the stem and branches. 

 Whan they first escape to the surface they are fluid, and of a light 

 colour, but gradually harden, and become of a deeper hue, either by 

 the evaporation of some of their volatile oil, or by the absorption of 

 oxygen from the air, and the conversion of the oil into a resin. Some 

 remain in a semi-liquid, viscid state, such as sagapenum and galbanuin, 

 which are only pulverisable in winter. Most gum-resins possess a 

 strong odour, which in many instances is disagreeable, such as that of 

 asafoctida, with a warm acrid taste, and by application to the skin for 

 any considerable time they cause redness and inflammation. Owing 

 to their composition being a mixture of gum and resin, they are not 

 completely soluble either in water or absolute alcohol, but are perfectly 

 dissolved in proof-spirit, which is much employed to prepare tinctures 

 of this class of substances. The gum being soluble in water is capable 

 for a time of holding the resinous portion suspended in water, thereby 

 forming an emulsion, a state which permits of their administration, 

 if used goon after being prepared ; for by rest they separate. Many of 

 them are soluble to a certain extent in acetic acid, especially when 

 assisted by heat. The strong mineral acids char them and produce 

 chemical changes. Many gum-resins are popularly termed balsams, a 

 designation to which they have no title, as they do not contain benzine 

 acid. 



Gum-resins are with difficulty soluble in the animal juices, yet, as 

 they must be assimilated before they produce their characteristic 

 effects, they require to be used for some time before the secretions of 

 the body acquire their peculiar odour. They influence the secretory 

 and excretory processes, which they rouse to continued action. They 

 also act upon the skin as sudorifics, and more permanently than the 

 volatile oils. They manifest their beneficial effects chiefly when the 

 skin is cool, pale, and in a state of atony ; and they can even check 

 profuse perspiration, when this is caused by the lax state of the 

 cutaneous tissues. They are likewise possessed of considerable anti- 

 spasmodic powers, and hence are much used in nervous complaints. 

 They greatly promote digestion when the stomach is feeble, owing to a 

 defective supply of nervous energy. Their utility in the treatment of 

 hysterical and other paroxysms is very much increased by adminis- 

 tering them in a state which admits of ready solution in the gastric 

 fluids ; hence the acetous preparations of them are much more potent 

 than any other form. They may be administered either by the mouth, 

 or, in case of spasm closing the teeth, or the patient being refractory, 

 in the form of clyster, the dose being doubled in the latter instance. 



Gum-resins are likewise applied externally, owing to their rube- 

 faciciit powers, in the form of liniments or plasters, in spasmodic and 

 rheumatic affections, and also to assist in dispersing indolent tumours. 



Gum-resins should be kept in cool well-closed places, to prevent the 

 evaporation of their volatile principles. 



GUMS AND OUM-TKADK. Professor Solly, in a paper on the 

 subject of Gum*, read before the Society of Arts, recommended to 

 drug-broken the adoption of a more exact classification than at present 

 prevails, between gums, resins, and gum-resins. Dealers and brokers 

 know very well what they mean ; but they are not so precise as 

 chemists in the nomenclature adopted. The distinctions recommended 

 are as follow, '/'ion* to comprise those natural vegetable exudations 

 which soften or dissolve in water, and yield a more or less perfect 

 mucilage, but which are wholly insoluble in spirit ; mint to comprise 

 those fusible and combustible vegetable substances which arc <miu- 

 insoluble in water, but which soften and dissolve in spirit, ether, or 

 essential oil ; and yum-reiini to comprise those natural product* which 

 are intermediate in properties, and partake of the nature both of gums 

 ami rain*, being partially and imperfectly soluble both in water and 

 in spirit. 



Different kinds of gum, limit. .1 and defined as above, arc extensively 

 used in the arts, especially in lininhing and giving lustre to crape and 

 n Ik goods, and in numerous processes of calico printing. One kind 

 alone, Gum Sencyai, baa been imported by a single Liverpool firm 

 to the value of lOO.OUO/. in three years; and the export of gum 

 from Alexandria has often reached 140,0001. per annum. The Cape 

 colonist* established a trade with the Kaffirs, a few yean ago, for gum 



which was obtained from the MI'MMO tree, and which was aent to 

 England for the uaa of calico printers, calenderen, envelope makers, 



be trade afterwards fell off, through the iin.-uti.iii or di- 

 of /.Vi'fu* ./, presently to be described. The east and wart shores 

 of the Red Sea are the chief sources for yam arabie (which scarcely 

 differs from gum Senegal) ; from two to three hundred tons pass 

 annually through the Custom House of Aden alone. Large quantities 

 are collected by persons in the employ of the Egyptian government, 

 and brought in caravans to Cairo to be warehoused ; in recent years, 

 the quantity has averaged about 20,000 packages of 78 Iba. each. The 

 produce of Morocco is packed in very large leather sacks, and conveyed 

 on tin' locks of camels and bullocks to the ports, where it is t- 



.li merchants; during the whole time, from the 



ng to the sale, including the land journey, the natives live 



almost wholly on the gum, a few ounces being sufficient to support a 



man for twenty-four hours. A gum exuding from the Maranmy or 



Indica in Travancore, is occasionally used for taking impress! 



oins, medallions, &c. ; when this gum is pure and carefully 

 prepared, the transparent casts are as sharp as those of sulphur, 

 without its brittleness. 



The gums proper are most largely used in the stiffening of textile 

 materials ; the resins proper are, for the most part, used in the making 

 of varnishes and lacquers, in dyeing, in paper-making, and in making 

 sealing-wax. The gum-resins are mostly used in medicine. Many 

 of these substances are of sufficient importance to occupy separate 

 articles in this division of the Cyclopicdia ; while the general cha- 

 racter of the uses of others can be inferred from the observations just 

 made. 



For some delicate processes in the arts, gum arabie and gum senega! 

 require to be purified. The following is one mode, patented a few years 

 ago, for effecting this : A solution of purified sulphurous acid gas 

 being prepared, the gum is dissolved in it, with exclusion of atmos- 

 pheric air. The earthy and ligneous impurities fall to the bottom ; the 

 colouring matters combine with the gas ; and the carbonic acid is 

 driven off by the application of heat. Carbonate of baryta, or some 

 other Bolidifiable base, is added ; this combines with the sulphurous acid 

 and forms a neutral salt. The solution is then filtered through n pure 

 gelatinous hydrate of alumina ; and is finally dried by heat, either in 

 the open air or in vacuum pans. 



Mention was made above of Ilrititli yum, as a substance which has 

 lessened the use of foreign gums in this country. According to an 

 account given by Mr. Simmonds, a fire on one occasion broke out in a 

 potato-starch manufactory in Dublin. The burning building was 

 deluged with water by the fire-engines, and the starch was washed 

 about in every direction. One of the workmen fell down, and had his 

 clothes soaked with the calcined starch and water. He thought no 

 more of it till the next morning ; when, upon dressing himself, he 

 found the sleeves of his coat, the legs of his trousers, and the linings 

 of his pockets, glued up so that he could with difficulty open them. 

 On revisiting the scene of the fire, he discovered that the glutinous 

 properties were possessed by the potato starch ; and by a few simple, 

 experiments, a discovery was completed which has resulted in large 

 profits. Under the names of Jirilith gum, dextrine, and yum-tukiiilute, 

 a new substance appeared in commerce, and became largely employed 

 in the arts. It ia nearly equal to gum arabie in adhesiveness, less 

 affected by climate, and less than one-fourth of the price. It forms 

 the main ingredient in the adhesive composition for cm. lo|>es and 

 postage-stamps. For the chemical qualities of this substance, see 

 DKXTIUNE. 



It is not easy to state the quantity and value of gums, resins, and 

 gum-resins imported into this country, and mostly used here in 

 manufactures and in medicine. They are scattered about under so 

 many headings in the official lists, and are entered under such cli 

 forms, that they can scarcely be recorded collectively. Tl 

 importation amounted, a few years ago, to 2200 tons annually, including 

 the heavy items of turpentine, resin, caoutchouc, and gutta-percha ; 

 but the importation of the last two substances has since prodigiously 

 increased. [CAOUTCHOUC; GUTTA-PERCHA.] Four of the most costly 

 substances in the above list, those which present the m.wt value in the 

 smallest space, were imported into the United Kingdom in the 

 following quantities and values in 1856 : 



Cwts. . 



Gum copal . 



Cum arable 

 Loo dye . 



MII ;1 lac . 



6,300 

 70,900 

 11,000 

 14,800 



16,700 



120,800 



37,500 



34,700 



M my \.ui.tii-.-t of giiiu are included in the official entry, Gum 



(il'N IH a term now generally applied to the larger description of 

 file aim, but as a description of the principal varieties of fire-arms, 

 l>..tli large .MM -mall, with notices respecting the dates of their invcn- 

 givcn under Atiilx and A K, 11,11 in, and under CANNON is an 

 account of the manufacture of gn I shall here Hupply a 



notice of the manufacture of the smaller kinds of fire-arms, to which 

 the names of musket or uiusquet, fowling-piece, &c. are applied. 



The rise of the gun-manufacture in Birmingham, which is its prin- 

 cipal scat in this country, appears to date from about the conn 



