581 



GUTTA-PERCHA MANUFACTURE. 



GUTTA-PERCHA MANUFACTURE. 



582 



or gum-exuding group ; the wood, soft and spongy, is not of much use ; 

 the fruit yields a thick oil. which the natives mix with their food, and 

 from which an" ardent spirit can be obtained. The sap, which forms 

 the most valuable product, circulates in small vessels between the bark 

 and the wood; by tapping, or cutting notches in the branches at 

 certain seasons, it flows out without endangering the life of the tree. 

 How far the process can be so managed as to obtain a continuous or 

 periodical supply from the same tree, is a problem not yet solved. 

 The sap flows out into vessels held underneath. Before it is con- 

 solidated by the action of the air, the gatherers knead it into lumps by 

 the hand or by a piece of wood; it is brought into any shape at 

 pleasure, but usually comes to market in the form of roundish lumps, 

 eight or more inches in diameter. Most of the gutta-percha of the 

 Eastern Archipelago comes to Singapore as the chief market; and 

 the buyers too often find it adulterated with wood, stone, and 

 other impurities, to increase the weight ; there is also much refuse 

 of bark, leaves, and dirt mixed up accidentally with it. On these 

 accounts, all the specimens are narrowly scrutinised on reaching 

 the London market, to determine their net value when freed from all 

 impurities. 



Before gutta-percha can be applied to any of the numerous purposes 

 fur which it is now known to be valuable, it requires a great deal of 

 preparation. The preparatory processes are peculiar, on account of the 

 remarkable toughness of the substance. The masses are first cut into 

 slices, by means of a wheel provided with knives or blades ; the wheel 

 revolves two or three hundred times in a minute, and the slices are cut 

 as if by a turnip cutter. If there are any stones or other hard 

 impurities in the lumps, the slicing detects it ; the cutting edges are 

 blunted, and the adulterants require to be removed. The gutta-percha 

 varies much in colour, consistency, and other qualities, even in the 

 same mass ; and a thorough mixing becomes necessary. The slices are 

 thrown into a tank of water, heated by steam ; the dirt and heavy 

 impurities fall to the bottom, leaving the gum as a pasty mass. The 

 gum is then transferred to a rotating machine, where sharp jagged 

 teeth rend and tear it asunder with great violence ; the fragments fall 

 down into water, where they float. After another softening in hot 

 water, the gutta-percha is transferred to a kneading trough ; this is a 

 kind of cylinder, kept hot, in which revolving drums knead and roll 

 the substance most completely, rendering it as homogeneous as possible 

 in all parts. The shapeless but purified mass is next brought into 

 certain forms, preparatory to its useful application in the arts. These 

 forms may be blocks, slabs, sheets, or tubes. In forming sheets, the 

 gutta-percha is passed between steel rollers, placed at a distance apart 

 corresponding with the thickness of the sheet to be made. By the 

 adjustment of a few knife edges, these sheets may be cut into bands 

 or strips of any width. In making tubes or pipes, the gutta-percha is 

 s-ofti-ned, and passed through heated iron cylinder.*, where it is reduced 

 to size and form by a kind of wire-drawing process. 



To estimate the actual and prospective uses of this singular sub- 

 stance, we must take note of its projjerties. The toughness of gutta- 

 percha, differing from the elasticity of caoutchouc, and the facility with 

 which it may be softened by heat, render it fitted to receive and retain 

 any form that may be given to it. It is very easily pressed in moulds, 

 while in a warm aad plastic state. Whether wet or dry, its uses are 

 confined to cold purposes, as it is soon affected and thrown out of shape 

 by heat. For many purposes, naphtha and other inflammable liquids 

 act as cements and solvents for it. Its surface is susceptible of being 

 so prepared as to receive paint, gilding, japanning, burnishing and other 

 decorative modifications. Its remarkable relation to electricity renders 

 it an invaluable substance for coating telegraphic wires. Its stubborn 

 resistance of the corroding action of many powerful acids, alkalies, and 

 salts, fits it for use in vessels and pipes for chemical operations. Its 

 impermeability to water has brought it largely into use as a sheeting 

 for damp walls and other places. 



The works of the Gutta-Percha Company, in the City Road, are the 

 largest in any country; and a list of the articles made in that establish- 

 ment would show into how many departments of every-day life the 

 use of this substance has extended. Such a list need not be given 

 here ; for every week would add something to its length ; but the uses 

 might easily, if neoetsary, be grouped into such headings as domestic, 



'I, rhrmiral, mrtniifac/vriny, agri<-i'l'nr>il. MtMr" 

 engineering, and ornamental. The gutta-percha, when applied to these 

 uses, is in form of a sheet, a strip or ribbon, a rod, a tube, a cord, a 

 cloth, Ac. ; and many processes, especially stamping, are employed to 

 fashion the gutta-percha into the desired shapes. The gum possesses 

 much value as a material for water-pipes ; it is strong and tough ; it 

 resists frost ; it leaves the water as pure as it finds it ; it will bear 

 a great amount of friction and hard usage ; it resists the action of 

 marine insects; it is conveniently flexible as a material for hose 

 for watering gardens and roads, and sprinkling malt ; and it is recom- 

 '<! by many physicians as a substitute for lead pipes, on 

 account of the deleterious nature of the latter. A gutta-perchn 

 tube three-quarters of an inch in diameter, and one-eighth of an 

 inch thick, has been found to bear an internal pressure of 500 Ibs. on 

 the square inch, without bursting ; it yielded a very little, and then 

 resumed its original form. The Americans, in carrying the water of 

 the great Croton aqueduct into New York, laid down a gutta-percha 

 pipe, a thousand feet in length, along the bed of nn intervening river, 



where it was kept down by anchors ; the pipe bore the pressure of the 

 aqueduct water within it and the river water around it, as well as the 

 weight of the moorings and the friction of the bed. In a wholly different 

 department of application, gutta-percha is singularly valuable ; no other 

 known substance equals it for acoustic properties. The sonorous 

 vibrations of the air are less stifled in a gutta-percha tube than in one 

 made of any other substance ; hence the extensive use o this material 

 for speaking-tubes, ear-trumpets, domestic telegraphs, &c. ; it assists the 

 hearing of partially-deaf persons, and transmits the sound of the 

 voice to a distance which would otherwise render it inaudible even to 

 sensitive ears. The electric insulating properties of gutta-percha are 

 now well known, as among the most indispensable conditions for 

 telegraphic communication. In land electric-telegraphs, there is no 

 occasion to coat the copper-wires with gutta-percha, provided the 

 supporters are made sufficiently insulating; but for the submarine 

 wires such an envelope is necessary, to prevent the electric current 

 from diffusing itself in the surrounding water. Wires coated with gutta- 

 percha have also been found serviceable for igniting blasts of powder, 

 in great engineering operations. Gunpowder has been blasted at one 

 end of a wire 70 miles long, by a galvanic current sent in at the other 

 end. In its form as a sheet, gutta-percha is used in many situations in 

 contact with cold water, on account of the ease with which it can be 

 cut and cemented, and the way in which it resists moisture. It has in 

 this way been successfully applied as a lining for cisterns ; as a 

 material for water-buckets and valves; and as an extra sole for boots 

 in wet weather. Some of the boats made of gutta-percha have 

 presented very remarkable qualities. Mr. Snow, who had charge of a 

 gutta-percha boat in the arctic ship Prince Albert, said : " The 

 severest trial it endured, and endured successfully, was in both my 

 visits to Whaler Point, Port Leopold. To those unaccustomed to the 

 nature of such ice as was there met with, it will be impossible fully to 

 conceive the position a boat was placed in. The mere transit to and 

 fro, among loose masses of ice, with the sea in a state of quiescence, 

 would have been quite enough to prove the value of gutta-percha 

 boats; but when, as in the present case, those masses were all in 

 restless agitation, with a sea rolling in upon an opposing current, it 

 might have been well excused and without deteriorating from the 

 previously-attested goodness of the article if it had not been able 

 to resist the severe shock it received. . . . Sliding through and over 

 the ice; sometimes lifted completely out of the water by the sudden 

 contact of a restless floe, and at others thrown sideways upon an 

 adjoining craggy piece, I think it would have been next to impossible 

 for any other kind of boat to be otherwise than crushed or stoved on 

 the instant." The name of Gutta Percha Inlet was given to the place 

 where this boat had rendered such valuable service. 



Widely different from any of the above-named uses, are those in which 

 gutta-percha is employed as a material in decorative art. It is fitted 

 for such purposes chiefly in virtue of the facility with which it takes the 

 impress of a stamp or mould when heated, and the correctness with 

 which it maintains that impressed form when cold. The mould may 

 be of metal, wood, or almost any other material. One of the most 

 frequent modes of producing the casts is this. A piece of sheet gutta- 

 percha is laid upon a steam heated slab of marble or stone ; when 

 sufficiently softened, it is laid upon or in the mouM, a counter-mould 

 i* hiil upon it, and a screw-press finishes the process. If the pattern 

 be in very bold relief, a hydraulic-press may be necessary ; but in most 

 cases a hand-press supplies a sufficient degree of force. Some years ago 

 the Irish Patent Office adopted gutta-percha as a material for the seals 

 of patents, on the ground that it gives bold and sharp outlines, and is 

 free from the odour, brittleness, and greasiness of the yellow wax pre- 

 viously employed ; but this novelty has, we believe, not been retained by 

 the commissioners of patents. It is by a process of pressing in moulds 

 that a vast number of articles are made in gutta-percha, useful in their 

 application and ornamental in their appearance. Sometimes a dextrous 

 workman will give a clouded or grained or veined appearance, by avail- 

 ing himself of the different tints which different pieces of gutta-percha 

 present; when the surface is polished, this diversity gives rise to much 

 beauty of appearance. More closely associated with h'ue arts are those 

 processes in which gutta-percha assists in a kind of engraving or trans- 

 ferring for which see ENURAVIXII; PRINTING ; I'IIOTUUKAPHY. 



I n all that has been said hitherto concerning gutta-percha, the use 

 of that substance by itself is implied ; but much ingenuity ha* 

 been displayed in producing combinations. One among the many 

 modes of employing gutta-percha as a material for models, moulds, 

 medallions, <fec., is that of Duthoit, a French inventor. The gutta- 

 peroha is first dissolved in naphtha, then filtered, and then put into a 

 still, with the addition of oxide of zinc, sulphate of barytes, amianthus, 

 and one or two other substances. When the mixture has been well 

 stirred, heat is applied, and the volatile elements driven off. The 

 composition being taken out of the still, is ready for use. Colouring 

 matter is either put into the still with the other ingredients, or it is 

 mixed afterwards by masticating the composition with it, in presence 

 of warm water containing a little soda. The substance thus prepared 

 is suitable to make not merely models and moulded articles, but also 

 tissues, artificial-flowers, and a substitute for leather. If diluted with 

 naphtha or benzole, the composition may be used as a liquid paint. 

 Some of the compositions are intended to liquefy rather than harden 

 the gutta-percha : such a that of dissolving the gum in carburet of 



