The geographical distribution of the trees producing gutta percha is very restricted. Giitzlaff defines the limits as 6° N. and S. lat. and 100° to 120° E. long.; whilst Captain Lingard (who has great personal experience on the subject) gives the limits as 4° N. and 3° S. lat., still further restricting the finer varieties to 3° 50' N. and 1° S., with a temperature ranging between 66° and 90° Fahr., and a very moist atmosphere. These limits are well within the isotherm of 80° Fahr. Many of the best varieties are found only on the hill slopes at a distance from the sea-coast, each variety forming a separate grove of from 200 to 500 trees, with high forest trees above them. They grow best in a rich light loam, with a rocky subsoil.
The collection of gutta percha generally takes place directly after the rainy season, as in the dry season the gutta does not flow so readily, while during the rains ague and jungle fever are most prevalent, and the gutta is liable to be washed away from the felled trees. The yield of a well-grown tree of the best variety is from 2 to 3 lb of gutta percha, such a tree being about thirty years old, 30 to 40 feet high, and 1⅜ to 3 feet in circumference. A full-grown tree sometimes measures 100 to 140 feet to its first branches, with a girth of 20 feet at a distance of 14 feet from the base, and may yield 50 to 60 δ> of gutta percha, which loses in six months about 35 per cent, of its weight in drying.
The methods of extracting the gutta percha are much the same amongst the Malays, Chinese, and Dyak3, The trees are cut down just above the buttresses, or banees, as they are called; and for this purpose a staging about 14 to 16 feet high is erected. The tools used in felling are either rt billiôngs” or “parangs.” A billiong is a kind of axe used by the Malays in felling, building, &c. The blade is of a chisel-like form, and the tang is secured at right angles to a handle by means of a lashing of “ratan” or cane. The Chinese sometimes use an axe perfectly wedge-shaped. The parang looks more like a sword-bayonet, and in the hands of a Malay is a box of tools in itself, as with it he can cut up his food, fell a tree, build a house, or defend himself.
When the tree is felled the branches are speedily lopped off, to prevent the ascent of the gutta to the leaves. Narrow strips of bark, about an inch broad and 6 inches apart, are then removed, but not all round the tree, as its underpart in its fall becomes buried in the soft earth, much sap being thus lost. Some natives beat the bark with mallets to accelerate the flow of milk or gutta. The milk flows slowly (changing colour the while) and rapidly concretes, and, according to its source, may vary from yellowish-white to reddish or even brownish in hue. The gutta as it flows is received into hollow bamboos, doubled-up leaves, spathes of palms, pieces of bark, cocoa-nut shells, or in holes scraped in the ground. If the quantity obtained is small, it is prepared on the spot by rubbing it together in the hands into a block, in one end of which a hole is made to carry it by. In this state it is known in the market as “raw gutta” or “gutta muntah.” If water gets mixed with the juice, the gutta becomes stringy and is considered deteriorated, but after boiling appears quite as good. Sometimes the gutta is kept in a raw state for a month or two, and then undergoes the next step in the preparation, that is, boiling. The boiling is generally conducted in a “kwali” or pan of cast or hammered iron, of about 15 inches in diameter and 6 inches deep. The boiling iβ either simply with water, or with the addition of lime juice or cocoa-nut oil. If one pint of lime juice be added to three gallons of gutta juice, the latter coagulates immediately on ebullition.
On arriving at the port of shipment the gutta, before exportation, generally undergoes examination and classification into parcels, according to quality. As received in the “godowns” or warehouses it presents great diversities in condition, shape, size, and colour,—from crumbling, hardly coherent, whitish or greyish “raw” or “getah muntah” fragments, to reddish or brownish blocks as hard as wood. Sometimes it is made up into all manner of grotesque shapes of animals, and it is nearly always largely adulterated with sago-flour, sawdust, clay, stones, &c. The Chinese are great adepts in assorting and classifying gutta, and frequently prepare from different varieties a certain “standard sample” by cutting or chopping the material into thin slices and boiling with water in large shallow iron pans, keeping the contents constantly stirred with poles, and adding good gutta percha and even cocoa-nut oil to give a better appearance. When sufficiently boiled the gutta is pressed into large moulds, and is then ready for shipment. This process of reboiling is wholly unnecessary, and in some cases is done only to get rid of stuff which has no right to be called “gutta percha.”
The amount and value of gutta percha imported into Great Britain in 1875-77 were as follows :—
[table]
The price of gutta percha ranges from 4d. to 3s. per fi>, according to quality and demand.
History.— The early history of the use of gutta percha is somewhat obscure; the Malays and Chinese are said to have long known and used it. One of the earliest notices of it in England occurs in a catalogue of the collection of the famous Tradescants. Dr Montgomerie, a surgeon in the East India Company’s service, was the first to direct attention to gutta percha as likely to prove of great utility in the arts aud manufactures. Having observed the substance in Singapore in 1822 in the form of whips, he commenced experimenting with it. In 1842, being again stationed at Singapore, he followed up the subject, and his recommendation of it to the medical board of Calcutta as useful for making of splints and other surgical apparatus met with high approval. He also sent specimens, with relative information, to the Society of Arts of London, which society warmly took up the subject, and on Montgomerie’s return to England in 1844 presented him with its gold medal. Some have claimed the honour of introducing gutta percha to the notice of the commercial world for Dr (afterwards Sir) José D’Almeida, who sent a specimen merely as a curiosity to the Royal Asiatic Society in 1843, but careful investigation clearly,, decides the question of priority in favour of Montgomerie. The Society of Arte having requested him to lay before them the result of his experiments, he delivered a lecture in the autumn of 1844, and many patents were at once taken out, the chief being those of Mr C. Hancock, Mr Nickels, Mr Keene, Messrs Barlow and Forster, Mr E. W. Siemens, and others. After this the substance soon came into general use. Properties.— Gutta percha, like many other milky juices, occurs in the laticiferous tissue of the plant, which exists in greatest abundance in the middle layer of the bark. See Botany, vol. iv. p. 87.
Gutta percha is resolvable into two resins, αlbiη and fiuavil. Like caoutchouc or india rubber, it is a hydrocarbon; Soubeiran gives its composition as—carbon 87'80 and hydrogen 12 , 20. In commercial gutta percha we have this hydrocarbon or pure gutta, phis a soft resin, a resultant of oxidation of the hydrocarbon. Μ. Payen gives the following analysis of commercial gutta percha :—
Pure gutta (milk-white in colour and fusible), 75 to 82 per cent.
Besins soluble in boiling alcohol :—
1. Crystalbin or albin (C 20 H 32 O 2 ), white, and crystallizing out of the alcohol as it cools, 6 to 14 per cent.
2. Fiuavil (C 20 H 32 O), yellow, falling as an amorphous powder on the cooling of the alcohol, 6 to 14 per cent.
It is thus apparent that the change of pure gutta into a resin-like mass takes place naturally if means be not taken to stop it. Many a good parcel has been thus lost to commerce, and the only remedy seems to be thorough boiling.as soon after collecting as possible. It must be remembered too that, in cutting through the bark to arrive at the laticiferous vessels, many other vessels and cells become ruptured, containing tannic and gallic acids, &c., and the presence of these no doubt accelerates oxidation. In opening bottles of the milky juice a turbidity and effervescence are often noticed, owing to the formation of a brownish liquid, the colour being probably due to the presence of gallic acid. In improperly prepared blocks of gutta also, these foreign substances induce the presence of a brown fermented and putrid liquid, which decomposes the internal mass. Many of these substances, being soluble in water, are removable by the process of boiling.
Gutta percha as met with in commerce is of a reddish or yellowish hue, but when quite pure is of a greyish-white colour. In this state it is nearly as hard as wood, only just receiving the impression of the nail, is of a porous structure, and when viewed under the microscope has the appearance of a series of variously hued prisms. When moulded, rolled into sheets, or drawn into ropes, it. assumes a fibrous character in the direction of its greatest length, in which direction consequently it can be stretched without rupture. If, however, a strip of a sheet be cut off across the fibre, it will be found that a redistribution of the tenacity of the slip takes place; i.β., the direction of the fibrous character is developed in an opposite direction. The electrical properties of gutta percha were first noticed by Faraday. If a piece be subjected to friction, an electric spark can be obtained. On its relative electric conductivity, see vol. viii. p. 53.
At a temperature of 32° to 77° Fahr., gutta percha has as much tenacity as thick leather, though inelastic and less flexible. In water at 110° Fahr, it becomes less hard; towards 120° Fahr, it becomes doughy, though still tough; and at from 145° to 150° it grows soft and pliable, allowing readily of being rolled and moulded. In this state it has all the elasticity of caoutchouc, but this it loses as it cools, gradually becoming hard and rigid again, and retaining any form impressed on it whilst in its plastic condition. It is highly inflammable, and buras with a bright flame, dropping a black residue like sealing wax. The specific gravity of gutta percha has been variously stated at from 0 , 9β285 to 0 - 99923. It is insoluble in water, alcohol, dilute acids, and alkalies, but dissolves in warm oil of turpentine, bisulphide of carbon, coal tar oil, caoutchin or oil of caoutchouc, and its own oil,—for it yields by destructive distillation an oil similar to that yielded by caoutchouc under the same treatment. Ether and some of the essential oils render it pasty, and it is softened by hot water, absorbing a small quantity of the water, which is slowly parted with in cooling.
Manufacture and Applications.— Gutta percha, as received in England, is in irregular clumps or blocks, and is frequently adulterated with massive stones, sawdust, bark, sago flour, and other foreign matters; and the first step in its manufacture is to cleanse it thoroughly. The blocks are first sliced by means of a powerful circular wheel driven by machinery, and having fixed in it two or three strong chisel-like knives, by which it is divided into thin slices. These are placed in wooden troughs filled with water and heated by steam. As soon as the gutta percha becomes soft, it is taken out in baskets and placed in a toothed iron cylinder, called a “devilling” machine, which tears it into fragments; these fall into a trough of water, and the impurities sink to the bottom, leaving the purified gutta floating in the form of a spongy mass. This mass is then taken out by means of perforated shovels, thoroughly washed in cold water, and dried in baskets. It is then packed in jacketed iron chests heated by steam, and left till it becomes soft, when it is at once removed, and kneaded or masticated by means of a cast-iron cylinder, with a movable lid and an internal revolving toothed iron axis,—the result being a homogeneous dough-like reddish-brown mass. Sometimes various substances are introduced into this machine, which is called a “masticator,” to increase the hardness or density of the gutta, or to colour it,—such as orange or red lead, chrome, vermilion, yellow ochre, sulphur, caoutchouc, gypsum, or resin, care being taken to use such substances only as are not affected by the heat necessary in the operation. The incorporation is conducted with great nicety, as at the will of the operator a soft and elastic or a hard and horny substance can be produced. When sufficiently masticated, the gutta is placed whilst still hot between two steel cylinders, and thoroughly rolled. By means of an endless band of felt the gutta is returned again to the cylinders, the distance between which is gradually diminished so as to compress and completely drive out any contained air from the gutta percha. There are various machines for cutting driving bands, &c., to a uniform width, and for rounding off the edges and finishing. Soles for boots are made by cutting a long strip of the requisite width, and then passing the strip under a hollow die.
In making piping a machine is used consisting of a cylinder, with a die-piece attached of the requisite size. By means of a piston the gutta percha, which is introduced into the cylinder in a plastic condition, is drivên through the die-piece, and the piston gives the inner diameter of the piping. As the piping issues from the machine, it passes immediately into a trough of water, which “sets” it, and prevents it from collapsing. The value of gutta percha piping is very great: it does not contaminate water as lead piping does; it withstands insects, damp, &c., and is easily manipulated, being shortened, lengthened, or repaired without trouble or expense; and its acoustic properties have led to its employment largely in the manufacture of aural, stethoscopical, and other instruments. Gutta percha speaking-tubes are now to be seen in nearly every office. The substance too, from the fact that few acids and alkalies affect it, especially if dilute, is largely employed for funnels, siphons, and other chemical apparatus.
In telegraphy gutta percha is of the very highest importance, being a cheap, lasting, and powerful insulator, easily applied to telegraphic wires. The general method of coating telegraphic wire is by charging a cylinder with plastic gutta percha, and forcing it through a die-piece, the wire forming a central core. As the wire is drawn through this “die” or “moulding” piece, it becomes coated to the requisite thickness, and after passing through water it is wound on drums ready to be coated with tarred rope, and with galvanized iron wire if required for submarine cables.
The readiness with which gutta percha, whilst in its plastic condition, receives an impression, which it retains when cold, early led to its employment in the decorative and fine arts, since it reproduces the finest lines, as in the taking of moulds from electrotypes. See Electrometallurgy.
In the production of imitations of oak and other ornamental woods, gutta percha has been largely used, since by the admixture of various substances “graining” or marbling” can be very naturally represented, and a coating of a solution of gutta percha gives a varnish of great brilliancy.
Substitutes.— Many substances have been recommended as substitutes for, or as supplementary to, gutta percha. Among these Balata gum undoubtedly holds the first place. It is obtained from the Mimusops Balata (Gartner), a tree found in British and French Guiana, Jamaica, &c. Prof. Bleekrod seems to have been the first to direct attention to this substance, by bringing it before the notice of the Society of Arts in 1857. The Balata gum combines in some degree the elasticity of caoutchouc with the ductility of gutta percha, freely softening and becoming plastic, and being easily moulded like gutta percha. What small parcels have been sent to England have met with a ready sale, and were remarkably pure and free from adulteration. But unfortunately, through the difficulty of collection, the occupation being dangerous and unhealthy, the supply of this excellent article has fallen off. It is procured by making incisions in the bark of the tree about 7 feet from the ground, a ring of clay being placed around to catch the milk as it exudes. A large tree is said to yield as much as 45 lb of “dry gum.” Pauchontee, the produce of Bichopsis elliptica, Collins (Bassia elliptica, Dalzell), is a most interesting substance, and may yet prove an article of commerce if properly treated; at present, although by heat it becomes plastic and ductile, it is brittle and resin-like when cold. The tree is found very generally distributed in Wynaad, Coorg, Travancore, &c.
Many of the euphorbias yield milky juices which have some at least of the properties of gutta percha. The chief amongst these are the cattimandoo (Euphorbia Cattimandoo, Elliot) and the Indian spurge tree (E. Tirucalli, Linn.) of India, and some euphorbias at the Cape of Good Hope. The alstonia or pala gum (Alstonia scholaris, R. Br.) and themudargum (Calatropis gigantea, R. Br.), have also been recommended as substitutes for gutta percha. But the attempts made to utilize these substances have as yet been unsuccessful.
Future Supplies.— A very important matter for consideration is the question of the future supplies of gutta percha. It is after all only a spontaneous natural product. If a Malay or Chinese wishes to plant pepper, gambier, &c., he burns down a portion of the forest, and whén he has raised two or three crops he clears a new portion, and thus finely wooded spots become denuded of trees, and covered with rank grass rendering them unfit for further cultivation. Again, to obtain the gutta percha the trees are cut down, and none are planted in their stead, so that in districts where they were in abundance one or two only are now preserved as curiosities. It is a wonder indeed that a single tree is left. A writer in the Sarawak Gazette says that from 1854 to 1875 over 90,000 piculs (of 133⅜ K» each) of gutta percha was exported from Sarawak alone, and this meant the death of at least 3,000,000 trees. In fact the only thing that preserves the treo at all is that it is of no use to cut one down till it is 25 to 30 years old. Sooner or later recourse must be had to cultivation and conservation. (J. CO. )...
