464 



GULLET 



GUMMING 



ordinary to the Queen. He became a Fellow of the 

 Royal College of Physicians (1848) and of several 

 other medical and learned societies, as well as 

 president of the Clinical Society. Sir W. W. Gull 

 has published numerous papers and addresses, as 

 Reports on Epidemic Cholera ( with Dr W. Baly ) 

 in 1854; Gulstonian Lectures on Paralysis; the 

 Hunterian oration in 1861 and the Harveian in 

 1870 ; Clinical Observations in Relation to Medicine 

 in Modern Times, in 1869 ; and Alcohol as a 

 Medicine and as a .Beverage (1878). Died in 1890. ' 



Gullet. See DIGESTION, Vol. IV., p. 814. 



Gulliver's Travels. See SWIFT. 



GlllU, a general term applied to certain exuda- 

 tions from- trees and plants, which are very different 

 in their chemical characters and their general 

 properties. There are, however, three classes of 

 gums which may be more particularly referred to 

 viz. those containing arabin, those containing 

 bassorin, and gum-resins. 



( 1 ) Gums containing arabin are best repre- 

 sented by gum-arabic, the ordinary gum of the 

 shops. This substance is found as an exuda- 

 tion on the bark of the Acacia Senegal, a 

 tree of some 20 feet in height, growing abund- 

 antly in western Africa. According to the care 

 taken in collecting it, it ranges from the pure 

 white or colourless gum of Kordofan to the dark- 

 reddish varieties imported from Senegal. Chemically 

 these are absolutely identical, and therefore a 

 single description will suffice. It occurs in irregular 

 lumps, somewhat spherical or vermicular (as in 

 Gum-Senegal). It is brittle, and shows a glassy 

 fracture. It dissolves readily in water, forming a 

 clear, viscid, adhesive solution ; but it is insoluble 

 in strong alcohol, glycerine, ether, oils, or chloro- 

 form. The addition of alcohol to a watery solution 

 throws down a precipitate of arabin, if a few drops 

 of hydrochloric acid nave previously been added. 



Medicinally it has very slight remedial powers, 

 but it is largely used in prescriptions for the 

 purpose of suspending insoluble substances in 

 mixtures. The finer varieties, owing to their cost, 

 are rarely found outside the druggist's shop ; but 

 in the manufacture of confections and in the arts 

 large quantities of the cheaper kinds are employed. 

 These are known under different names, indicating 

 the district from which they are imported. The 

 chief are : Senegal gum, found in large firm 

 reddish masses ; Suakin gum or Talka gum, forming 

 dull opaque-looking tears, colourless or brownish ; 

 and Morocco or Barbary gum. Cape gum is 

 derived from the Acacia horrida, a native of Cape 

 Colony, while Wattle gum is a very adhesive variety 

 obtained from Australia. East Indian gum is 

 an African product, being simply imported into 

 Bombay from the Red Sea. 



(2) Gums containing Bassorin. The chief of 

 these, Tragacanth, is obtained from various species 

 of Astragalus, low spiny bushes, natives of Asia 

 Minor and Persia. When the stem of one of these 

 plants is cut transversely it will be found that the 

 space usually occupied by the pith has the appear- 

 ance of a translucent gummy mass, which the 

 microscope shows to possess the structure of an 

 ordinary pith. If incisions are made in the bark, 

 this semi-solid exudes 'under pressure, and, accord- 

 ing to the nature of the incision forms flattened 

 wing-like masses, nodules or worm-like pieces. The 

 finest variety is known as Flake-Tragacanth, con- 

 sisting of flakes 1 to 3 inches long by 1 inch 

 in breadth. The surface is marked by wavy lines 

 and the flakes are much contorted. Tragacanth is 

 translucent, white and without lustre, somewhat 

 flexible, and not brittle, and with little taste 

 or smell. When placed in water it swells, absorb- 

 ing fifty times its weight of that liquid, and form- 



ing a thick mucilage. It .has no active medicinal 

 properties ; but it is much used for firming pill 

 masses and lozenges It enters into many 

 emulsions, for instance, that of cod-liver oil, and it 

 is sometimes employed as a stiffener for the hair. 

 It is used as a stiffening material for various textile 

 fabrics, and is much valued for this purpose, where 

 it is not desired to give gloss to the material. 



Besides these true gums, there are ( 3 ) the gum- 

 resins. In general terms these consist of certain 

 resins soluble in alcohol, and of the true gum, so 

 that it requires both water and alcohol to dissolve 

 them entirely. They are chiefly used in medicine 

 and perfumery, and may be said to form a connect- 

 ing link between the true gurns and the true resins, 

 commercially speaking. The principal are : ( 1 ) 

 Gum-Ammoniacum (see AMMONIACUM), (2) Gum- 

 Asafoetida (see ASAFCETIDA), (3) Gum-Benzoin 

 (see BENZOIN), (4) Gum-Galbanum (see GALBA- 

 NUM), (5) Gum-Gamboge (see GAMBOGE), (6) Gum- 

 Myrrh (see MYRRH), (7) Gum-Scammony (see 

 SCAMMONY ). There are many other gums known ; 

 but these are the ones most used in the arts and 

 medicine. Many also of the true resins, as copal, 

 anime, &c. , are called gums, but they are strictly 

 resins. See RESINS. 



Gum-substitutes are manufactured from various 

 forms of starch, either by baking, roasting or 

 chemical treatment, so as to convert the starch into 

 Dextrine (q.v). They are made on a very extensive 

 scale, and are largely employed in dressing calicoes 

 and other fabrics, also as a substitute for the more 

 expensive gums in gumming-paper, as in the case 

 of postage-stamps and labels, which are made 

 adhesive by dextrine. For this and some other 

 purposes, tne gum-substitutes are superior to the 

 real gums, as they are easily dissolved, and can be 

 spread more equally over a smooth surface. For 

 the chewing-gum in use in the United States, see 

 CHEWING-GUM ; and for gum-trees, see EUCALYP- 

 TUS, TUPELO, and LIQUIDAMBAR. 



Gumbiimen, a thriving town of East Prussia, 

 72 miles by rail E. of Konigsberg. Dating from 

 1724, it owes its prosperity to the settlement eight 

 years later here of many Protestant Salzburgers. 

 There are machine-works, &c. Pop. 10,206. 



Gum-boil, an Abscess (q.v.) near the root of a 

 tooth, and usually discharging itself towards the 

 mucous membrane of the gum, but sometimes 

 making its way more deeply towards the skin of the 

 face, and if allowed to burst there causing consider- 

 able deformity. Gurn-boil should be treated, in 

 the first instance, by protection against cold and 

 external injury, and free washing of the mouth 

 with hot water ; but as soon as the presence of 

 matter can be ascertained, it is usually a good prac- 

 tice to give vent to it by a pretty free incision. 

 Complete cure follows the removal of the tooth at 

 the root of which the inflammation has begun ; if it 

 be left the disease is apt to recur. If the abscess 

 threaten to burst through the skin, extraction of 

 the tooth is imperative. See TEETH. 



Gumming (in vegetable pathology Gummosis), 

 a disease which attacks the plum, cherry, peach, 

 and other stone fruit-trees, often proving fatal to 

 the limbs attacked, and ultimately also to the 

 whole tree in virulent cases. Recent observations 

 seem to prove that the cause of the disease is a 

 fungus named Coryneum Beijerinckii. The my- 

 celium of the fungus develops a ferment which 

 transforms the cell-walls, starch granules, and 

 other contents of the cells into gum. While in 

 some cases the mycelium is obviously the exciting 

 cause, in others the ferment only appears to be the 

 contagious agent. One point seems quite clear 

 the fungus cannot penetrate sound healthy bark 

 there must be some wound or abrasion before the 



