CHAPTER III.
GUTTA-PERCHA—ITS PROPERTIES, MANUFACTURE, &c.
The almost numberless uses to which this remarkable gum has been, and is applied, has awakened an interest in the public mind concerning its discovery, and its uses, and especially the different applications, and their methods.
The discovery of Gutta-Percha is comparatively recent. The first that was known of this wonderful production by Europeans, was in the year 1845. Dr. Montgomerie, an English gentleman, residing at Singapore, observed in the hands of a Malay woodchopper, a strange material used for a handle to his axe. Curious to learn its nature, he questioned the native, and ascertained that he procured it from a tree in the form of sap; that upon exposure to the air it became solid; also, that in immersing it in hot water it became soft and plastic, and could be moulded into any desired form. Dr. Montgomerie at once obtained samples of the material, which he forwarded to the London Society of Arts and Sciences, with a description regarding it. After subjecting it to various tests, the Society were unanimous in their opinion concerning its great value. They awarded to Dr. M. a gold medal for the valuable knowledge thus communicated to the manufactories of the world.
It is observable, however, that this substance may be said to have had two European discoverers, independent of each other; for the tree, and the gum which exudes from it, were discovered or observed by Mr. Thomas Lobb. This gentleman visited the islands of the Indian seas in 1842–3, on a botanical mission, as agent to Messrs. Veitch, the scientific and energetic florists of Exeter; and it was during his rambles that he became acquainted with the gutta-percha tree.
In proportion as the value of this substance has become known, so has a desire extended to ascertain the range of its growth in the East. It is now known that the gutta-percha tree abounds in that extreme south-eastern point of Asia, which obtains the name of the Malay Peninsula; in the neighboring island of Singapore; in the important Bornean island, which Rajah Brooke has been the means of making so familiarly known to us; and in various islands which constitute the Eastern Archipelago. There seems very little cause to apprehend any failure in quantity; for even if the present supply from the neighborhood of Singapore should be exhausted, the capabilities of more distant islands are quite beyond present calculation.
It appears that _percha_ (of which the pronunciation is _pertsha_, not _perka_ or _persha_) is the Malayan name for the tree which produces the gum; while _gutta_ is a general name for any gum which exudes from a tree. The tree belongs, of course, to the group in which botanists place _sapotaceous_ or gum-exuding genera. The wood of the tree, being soft and spongy, is applied to many useful purposes. The fruit yields a thick oil, which is used by the natives with their food; and either from this or some other parts of the tree an ardent spirit is capable of being distilled. But it is the sap which forms the most valuable product of the tree. It circulates in small vessels which run up between the bark and the wood.
Thrifty methods are teachable to rude islanders, as to more civilised men, when the advantages have been once made apparent. The natives around Singapore, when they first found a market for the solidified gum, proceeded ruthlessly to work; they killed the bird which laid the golden eggs, by cutting down the trees in order to obtain the gum. But they have now been taught better; it is shown to them how, by tapping or cutting notches in the branches at certain intervals of time, the sap may be made to flow, without endangering the life of the tree. Experiments are now being made to determine whether the gutta-percha tree can be planted so as to maintain a continuous and inexhaustible store of gum or sap; should these attempts succeed, the supply would equal any imaginable demand.
The gutta-percha is sold at Singapore by weight, according to the apparent quality of each lump; but, when the consignment reaches England, it is not unfrequently found that a large stone or a piece of heavy wood is imbedded in the heart of it, to increase the weight. It would entail a serious loss of time to cut open each lump at the time of purchase; so that at present Oriental honesty is rather an important element in the commercial value of this article. There is, too, a great amount of difference in the quantity of bark, leaves, and dirt, which become accidentally mixed up with the gum.
The crude gum is imported to the extent of about two millions of pounds annually.
GUTTA-PERCHA IN THE FACTORY.
The extensive and highly interesting establishment of the Gutta-Percha Company, situated near the City Road Basin of the Regent’s Canal, is worthy of attention even beyond the general average of such centres of industry, for the peculiar character of the substance operated upon necessitates the employment of new processes, new machines, and new tools. An incessant course of invention has marked the manufacturing history of this material during the brief period of its existence. If the gutta-percha is to be applied to some new useful purpose, tools and processes of novel character have to be employed; if an ornamental application is determined on, methods are adopted for developing any natural beauty which the grain of the substance may present; if an attempt be made to supersede leather, or wood, or papier-mache, or metal, by this singular gum, great pains are bestowed on a study of the special qualities to be imitated, and the process of imitation often requires operations and tools differing considerably from those before employed.
The first process consists in cutting the block into slices. There is a vertical wheel, on the face of which are fixed three knives or blades; and while this wheel is rotating with a speed of two hundred turns a minute, a block of gutta-percha is supplied to it, and speedily cut into thin slices—much on the same principle as a turnip-cutter performs its work. Woe to the steel edges if a stone be imbedded in the block.
These slices show that the gutta-percha is by no means uniform in different parts, either in color or texture. To bring about a uniformity is the object of the shredding or tearing process. The slices are thrown into a tank of water, which is heated by steam to such a temperature as to soften the mass; dirt and heavy impurities fall to the bottom, leaving a pasty mass of gum; and the mass being thrown into another rotating machine, is there so torn and rent, and dragged asunder by jagged teeth, as to be reduced to fragments. The fragments fall into water, upon the surface of which (owing to the small specific gravity of the material) they float, while any remaining dirt or impurity falls to the bottom. These fragments are next converted into a dough-like substance by another softening with hot water, and the dough undergoes a thorough kneading; it is placed in hollow heated iron cylinders, in which revolving drums so completely turn and squeeze and mix the now purified mass, that all parts become alike, and every particle presents a family likeness to its neighbor.
The kneaded state may be considered the dividing line between the preparatory processes and those which relate to the fashioning of the material. The soft ductile mass may be formed either into sheets or tubes. In forming sheets the mass is passed between steel rollers, placed at a distance apart corresponding with the thickness of the sheet to be made—whether for the heels of a rough-booted pedestrian, or for the delicate “gutta-percha tissue,” now so much employed by surgeons. By the time that the substance has passed through the rollers it has cooled sufficiently to assume a solid, firm consistency. By the adjustment of a few knife edges, the sheet may be cut into bands, or strips of any width, before leaving the machine. In making tubes and pipes, the soft mass of kneaded gutta-percha is passed through heated iron cylinders, where a singular modification of the wire-drawing process reduces it to the desired form and dimensions.
From the sheets and tubes thus made, numberless articles are produced by cutting and pressing. Machines, somewhat like those used in cutting paper, are employed to cut the gutta-percha into pieces. If for shoe-soles, a cutting press produces a dozen or so at one movement; if for string, or thread, narrow parallel slips are cut, which are then rounded or finished by hand; if for producing stamped decorative articles, the sheets are cut into pieces, and each piece is warmed and softened to enable it to take the impress of a mould, or die. But the mode of casing copper wire for electro-telegraphic purposes is, perhaps, one of the most singular applications of the material in the form of a sheet. Several wires are laid parallel, a strip of gutta-percha is placed between them, another strip is placed above them, and the whole are passed between two polished grooved rollers; the pressure binds the two surfaces of the gutta-percha firmly together and to the wires, while the edges between the grooves indent the gutta-percha so deeply, that it may easily be separated longitudinally, each slip containing its own core of copper.
GUTTA-PERCHA BOATS.
When Lady Franklin fitted out an expedition in search of her gallant husband, a year or two ago, Captain Forsyth, the commander of the vessel, took out with him a gutta-percha boat, presented for that purpose by Messrs. Searle. His account of the behavior of this boat, under the rough usage to which it was subjected in the ice-bound regions of the north, is most laudatory. He states that “whilst the other boats constructed of wood suffered much by the cutting of the young ice, the gutta-percha boat was not in the least damaged, and returned to England in almost as good condition as when she left, although she underwent all the rough work of the voyage.” Mr. Snow, who had especial charge of the gutta-percha boat belonging to the ‘Prince Albert,’ has detailed in a clear manner the remarkable way in which this material resists the rude buffetings of those regions. It must be remembered that the boat had a skeleton of wood and a covering of India rubber. Mr. Snow says, “The severest trial it endured, and endured successfully, was on 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 have proved or not 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 have resisted the severe shocks it received.... Sliding through and over the ice; sometimes lifted completely out of the water by the sudden contact of a resistless floe; and at others thrown side-ways upon an adjoining craggy piece; I think it would have been next to impossible for any other kind of boat to have been otherwise than crushed or stove on the instant.” It was in a right spirit that the explorers gave the name of “Gutta-Percha Inlet” to the spot where the boat had rendered them such important service.
GUTTA-PERCHA—MISCELLANEOUS APPLICATIONS.
A rare catalogue we should present, if all the useful applications of gutta-percha were duly set forth. We should have to speak of breast-coating for waterwheels, of galvanic batteries, of shuttle-beds for looms, of packing for steam-engines and pumps, of cricket and bouncing balls, of felt-edging for paper making, of curtain rings whose merit is noiselessness, of window-blind cord and sash lines, of clothes’ lines (recommended to the laundress as defying all attacks of weather,) of bosses for flax-spinning frames, of whips and sticks, of policemen’s and ‘special constables’’ staves, of flax-holders for heckling machines, of skates, of fencing sticks, of washers for the axles of wheels, of plugs or solid masses used in buildings, of buffers for railway carriages, of gunpowder canisters (which ‘keep the powder dry,’) of sheet-covering for damp walls, of linings for ladies’ bonnets, of jar covers, of sponge bags, of foot baths, of funnels, of goldsmith’s bowls, of bobbins for spinning machines, of covers for rollers, of book covers, of moulds for electrotypes, of coffin linings, of sounding boards, of portmanteaus, of beds for paper-cutting machines, of fine and coarse thread, of envelope boxes, of powder flasks, of portfolios, of a stopping for hollow teeth—a tolerable list, this, which shows how multiplied are the applications for which this singular vegetable product is available.
GUTTA-PERCHA—ORNAMENTAL WORK.
When softened by heat, this substance will take the impress of a mould or stamp with delicate precision; and in the course of a few minutes it reassumes its tough state, retaining permanently the pattern given to it. The power of application is thus unlimited, or limited only by the inclination of the purchaser. Whether the mould be of copper or of brass, of pear tree or of box, an impress can equally well be obtained from it. In practice, all these four materials are employed, and sometimes others. The mould being carved and in a state of readiness, the piece of gutta-percha (always, or nearly always, in the form of sheet) is laid upon a marble slab, which is heated by steam from beneath; and the gum being thus brought into a pliant and yielding state, it is placed on or in the mould, a counter mould is laid upon it, and the action of a press forces the material into the minutest parts of the device. If the pattern be deep and the relief bold, a hydraulic pressure of a hundred or a hundred and fifty tons is brought to bear upon it; but if of lighter and simpler character, a hand-press is brought into requisition.
In this way, aided by minor manipulation, are produced the varied and ever-increasing specimens of ornamental gutta-percha work. Trays are produced of every imaginable (or at least of every usable) form and pattern: bread trays, biscuit trays, cotton or work-table trays, counter or card-table trays, pen trays, pin trays, card trays, soap trays, shaving trays, &c. Then there are work-baskets and hand baskets, flower vases and bouquet holders, plates and platters, decanter stands and watch stands, bas-reliefs and alto-reliefs. The desk fittings admit of much beauty in this material; inkstands are produced in most diverse forms; while pen trays, paper weights, wafer boxes, envelope boxes, &c., are beginning to establish a formidable rivalry to the similar articles made in papier-mache. Beauty, pattern, graining, clouding, or whatever we may choose to term it, is produced in a very remarkable way on the surface of gutta-percha. Some specimens of gutta-percha are darker than others, and all have a tendency to darken by age; and the workman dexterously avails himself of these varying tints to produce a pattern. He softens two or more pieces, of different tints, passes them between two rollers to thoroughly unite and amalgamate them, and then presses them into the mould; leaving it to the freaks of chance to bring out the wavy lines, the curls, the streaks, the knots, which the intermixture of tints produces. This diversity is not very apparent at first; but it becomes developed when the substance is polished, and considerably enhances the beauty of the article produced.
GUTTA-PERCHA PIPES AND TUBES.
Water-pipes have had a few vicissitudes in their history. Those who remember the arrangements for the water-supply of London, in past days, will have been familiar, with the wooden pipes, formed of bored trunks of trees, which were wont to be laid down beneath the paving of the streets. These gave way to iron. The smaller pipes have chiefly been made of lead; but zinc in one quarter, brown ware in another, glass in another, have invaded the domain of lead. A new competitor now enters the field. Gutta-percha claims to be not merely an efficient material for water-pipes, but to possess certain sanitary qualities very important in this sanitary age of ours. It is very strong and tough (say the patentees); it possesses much durability underground; it stoutly resists frost; and it leaves the water as pure as it finds it. Hence it is applied to pump barrels, to ships’ pumps, to locomotive feed-pipes, to syphons and mine-pipes, and to fire-engine pipes. But if the testimony of medical men is to be deemed authoritative, the substitution of gutta-percha for lead as a material for water-pipes is a matter of yet higher import. Dr. Thomas Smith, of Cheltenham, states that “Many serious and alarming disorders, such as mania, epilepsy, sudden death, nervous affection, paralysis, consumption, hydrocephalus, heart disease, &c., owe their origin in some instances, their intractable character in others, to the gradual and continuous infinitesimal doses of lead, copper, &c., introduced into the system through the channel of our daily drink.” It appears that the carbonic acid contained in water has a tendency to combine with the lead of the pipe which contains it, and to generate a compound possessing poisonous qualities. That gutta-percha resists such action, all authorities agree; and although at first the gum imparts a slight taste to the water, this effect seems speedily to disappear.
There are many other circumstances which render tubes of this material very advantageous for the conveyance of water. It bears an amount of friction and hard usage which is frequently surprising. At New York there is a gutta-percha pipe a thousand feet in length, which conveys the water of the great Croton Aqueduct to Blackwell’s Island; the pipe lies along the bed of the intervening river, and is kept down by upwards of a hundred small anchors, and yet it resists both the friction of the bed and the weight of the anchors. With an immense pressure of water, gutta-percha pipes have been found to remain unharmed, where leather hose would be disrupted. It resists the action of marine insects, which would soon make ravages on stout timber. If water be contained in a gutta-percha pipe, it remains liquid at a temperature which would produce ice in almost any other pipes. For watering gardens and roads, for sprinkling malt in a kiln, for applying water from a fire engine, these pipes appear to be singularly well fitted, since, with a great power of resisting pressure, they may be bent, or twisted, or lengthened, or shortened, in any required degree. Nor is this material, _per se_, the only efficient part of such pipes; for a gutta-percha pipe may be firmly united to a metal pipe in five minutes, with no other cement than warm water; the end of the pipe being softened in warm water, and drawn over the end of the metal, the gum contracts on cooling so as to grasp the metal tightly, and thus form an impenetrable joint.
But if water be conveyed thus effectively through tubes of gutta-percha, the qualities of the material are still more remarkably displayed in the conveyance of chemical liquids. Few persons are so ignorant of chemistry as not to be aware that the stronger acids and alkalies play sad havoc with the vessels and tubes which contain them. On the other hand, there is an obstinacy of constitution about this singular substance which enables you to battle a whole host of formidable opponents. It does yield, certainly, to concentrated sulphuric and nitric acids; but if these acids in a weaker state be the liquids in question, or if muriatic, acetic, or hydrofluoric acids, or chlorine (all of which have a very destructive action), then the gutta-percha stoutly resists them, and renders good service. Carboys, pipes, dye-vats, flasks, funnels, bowls, ladles, syphons, troughs, measures, buckets—all are now made of this material, for use in chemical works, print works, dye and bleach works, and other establishments where strong chemical liquids are employed.
CEMENT EXPERIMENTS.
The chemistry of cement is a curious one; for the stony particles adhere with a force which is in some instances almost equal to the power of stone itself. The so-called Roman cement has long been famous for its cohesive property; but the Portland cement recently introduced far excels it. In an experiment lately conducted, two solid blocks were prepared, one of Roman and the other of Portland cement; and they were placed in such positions that weights might be suspended from them. The Roman cement yielded to a disruptive force of eleven hundred pounds, but the Portland cement stoutly maintained its integrity till rent asunder by a weight of nineteen hundred. But this cement has still more strikingly shown its strength when used as a mortar in brickwork. On a recent occasion in Hyde Park, a brick beam was built up with Portland cement as a mortar. The bricks were hollow, and were so ranged as to form a beam about four feet in height by two in width. This beam was rested at the two ends on supports more than twenty feet asunder, and weights were suspended from the centre; and not till the astonishing weight of nearly seventy thousand pounds was thus applied did the beam yield and break. It was not the actual binding power of the cement alone that resisted this enormous force, for thin slips of iron were introduced at different parts; but the experiment was intended to show how much strength might be obtained by hollow bricks and Portland cement, aided by a little iron.
STEREOTYPING FROM GUTTA-PERCHA.
Mr. Muir, of Glasgow, has invented a mode of stereotyping, managed in the following way. A page of common type is first set up, and well fixed: a warm cake of gutta-percha is applied to it, screwed down tightly, and allowed so to remain a quarter of an hour; when this gutta-percha mould is removed, it is brushed over with fine black-lead, and an electro-copper cast taken from it; the printing is then effected from this cast. It is found that gutta-percha constitutes a very convenient and efficient substance for the mould, owing to the readiness with which it can be softened, and its toughness when cold; while the electro-copper cast is said to bear the action of the printing press throughout a much greater number of copies than an ordinary stereotype plate.
The same inventor also practices a plan in which the gutta-percha performs not only its own work but that of the electro-copper also. A mould is taken from an engraved wood-block, in gutta-percha; and this mould, when brushed over with black-lead, is made to yield a cast also in gutta-percha, in an exactly similar way; and from this cast the impressions are printed. It seems difficult to conceive that, after this double process, all the delicate lines of a wood engraving should be preserved on the surface of such a material as gutta-percha; and yet, without this preservation, the method would be practically valueless.
ACOUSTIC USES OF GUTTA-PERCHA.
The conveyance of _sound_ is, perhaps, the most extraordinary service which gutta-percha tubes have yet rendered.
There are two qualities required in a speaking tube; first, that it shall concentrate a large amount of sound into a small space; and secondly, that it shall not stifle the acoustic vibrations within the tube itself. Any material will answer equally well, so far as the first-named quality is concerned, for it requires simply a trumpet-shaped mouth at one end, and a very small orifice at the other; but gutta-percha possesses rare qualities in respect to the second kind of service. Whether it is the smoothness of the texture, or the peculiar kind and degree of elasticity, or the relation of the substance to heat or electricity—whatever may be the cause, a tube of gutta-percha preserves sonorous vibrations with a surprising degree of clearness and equability; and the modes in which this quality are brought into useful requisition are also very numerous.
There is, for example, the _long ear-trumpet_, with a wide orifice at one end and a small one at the other; and there is the _portable ear-trumpet_, differing from the former only in bringing the speaker and the hearer closer together, by a ‘French-horn’ system of twisting in the tube. There is the _ear-cornet_, so small and neat that one may be almost invisibly attached to or near each ear. There is the _paraboloid trumpet_, in which the sound is echoed from a large concave receiver before it enters the tube. There is the trumpet with a long flexible tube, or with several tubes, so that several persons round a table can communicate in turn with the user. In short, there have been almost as many useful variations of the principle as there are variations in the social inconveniences of those who require such aid.
A different group altogether is formed by those contrivances which are intended to aid—not partially deaf persons—but those whom noise or distance would otherwise disenable from conversing together. Drivers of omnibusses now sometimes communicate with the conductors, and captains of steamboats with the engine-men, by gutta-percha tubes. But these are trifling services compared with such as the tubes render at greater distances. The _Domestic Telegraph_, as it has been called, is simply a gutta-percha tube conducted from one apartment to another: it is employed as a medium of transmitting messages, and saves many a weary footstep to those who are at the beck and call of others. The _Medical Man’s Midnight Friend_ (a lack-a-daisical sort of a title) is a gutta-percha tube extending from the ‘doctor’s’ street-door to the doctor’s bed, by which a message can be transmitted to the awakened practitioner, instead of merely the sound of his bell. In factories and large establishments such speaking tubes are advancing extensively in favor; for the communication between distant buildings is most complete. In printing offices, spinning and weaving mills, in union poor-houses, in hospitals and infirmaries, and in various other establishments of magnitude, the advantages are so self-evident that the use is becoming very general.
The church acoustic apparatus is in many respects the most interesting and remarkable of these highly curious applications. Let us conceive, for clearness of illustration, that in a remote pew of a church is a person who, though not deaf, yet fails in ability to hear what is said in the pulpit or reading-desk. A gutta-percha tube is laid down either on or beneath the floor from the pulpit to the pew—the material bends so easily that it may be carried in any form—and a small ivory or hard wood ear-piece is attached to one end, while the other end expands in trumpet-form. Now the remarkable circumstance is, that the required effect is brought about without necessitating the approach of the speaker’s mouth to the tube; his head may be two or three feet above, or below, or behind, or at the side of the trumpet-mouth; and yet the sound will reach the remote end of the tube in audible quantity. The truth is, that if the tube receives a _mouth-full_ of sound (which it can in any direction round and near the speaker), that quantity is so economised, and so faithfully conveyed to the other end, that it becomes condensed to an audible pitch; if the trumpet-mouth be large, and the ear-piece very small, we may liken the action to the condensation of many threads of sound into one; and the ear of the auditor becomes sensible to this condensed power. In practice, the trumpet-mouth is usually fixed to the front of the pulpit, mouth uppermost, and is stamped or moulded in an ornamental form consistent with the decorations of the pulpit. Beyond all this, the sound may be _laid on_, like gas, to any pew or any quarter of the church; for there may be a tube (which we will call the main-pipe) laid along the centre aisle, and lateral tubes may spring from this to any required spot. Some clergymen have what they call a _deaf pew_; that is, a pew in which those are congregated who may be collectively benefitted by this admirable apparatus. This contrivance has been used at some of the great meetings (four thousand strong) at Exeter Hall, by those to whom the speeches would otherwise have been little else than dumb show.
Gutta-percha has been discovered in the British province of Mergui, and though not precisely identical with the gutta-percha of commerce, it possesses all the valuable properties of that substance, including plasticity in hot water, and the power of insulating electric currents.
The tree from which the true gutta taban is produced (erroneously misnamed gutta-percha, a gum yielded by a different tree,) is one of the most common in the jungles of Johore and the Malay Peninsula. It is not found in the alluvial districts, but in undulating or hilly ground. There is a great uniformity in the size of the full grown tabans, which rise with perfectly straight trunks from sixty to eighty feet in height, and from two to three feet in diameter, the branches being few and small. The natives, after felling the tree, make an incision round it, from which the milk flows. This is repeated at distances of six to eighteen inches along the whole trunk. It appears that the taban, or milky juice, will not flow freely like India rubber, but rapidly concretes. Its appearance in this state, before being boiled, is very different from that of the article as imported and shipped. It has a dry, ragged look, resembling shreds of bark, and instead of being dense and tough, is light, and possesses so little cohesion that it is easily torn to pieces.
Various statements are made as to the produce of each tree, which is somewhat surprising, considering the uniform size of the trees. It takes twenty trees to produce one picul of 133 lbs., and as the exports of gutta-percha, from the commencement of the trade up to the close of 1853, amounted to 3,107 tons, it follows that upwards of one million trees must have been destroyed to obtain that quantity in nine years. The natives, however, do not appear to be under any apprehension that the trees will be extirpated, and smile at the probability when suggested; for it is only trees arrived at their full growth, or at least at a very considerable age, that repay the labor of felling them and extracting the gutta; and those of all inferior ages which are therefore left untouched, will, it is supposed, keep up the race.
The collection of the gutta has widely extended, embracing now the Johore Archipelago, Sumatra, Borneo and Java. Unfortunately, the quality has deteriorated by the admixture of other inferior gums, the products of different trees, which are often used to adulterate the taban.