This valuable substance has only been known in Europe within the last twelve years. It is the concrete juice of a large tree (Isomandra gutta) growing in certain parts of the Malayan Archipelago—hitherto chiefly obtained from Singapore. The first specimen of the inspissated juice which appeared in England was presented to the Society of Arts in 1843, but two or three years elapsed before a just sense of the importance of the substance began to gain ground. In 1845 the importation of gutta percha into England amounted to only 20,600 lb.; in 1848 it had reached 3,000,000 lb.; in 1852 it amounted to 30,580,480 lb.—a rate of increase which gives serious cause to doubt whether the supply will long be adequate to meet the demand; for it is unfortunately the case that the trees which yield gutta percha are not only limited in their growth to certain districts, and less abundant in quantity than india-rubber trees, but they have been subjected for several years to the barbarous and wasteful mode of cutting down the trees for the sake of the sap. Whatever European industry may be able to do in checking this destructive system, and extending the cultivation of the gutta percha tree, there is yet reason to doubt whether this slow-growing tree can be reared in sufficient quantities to counterbalance the havoc already made. The Isomandra gutta belongs to the natural order Sapotaceae, and is the only tree which yields gutta percha. It rises to the height of 60 or 70 feet, and the trunk is 3 or 4 feet in diameter. The tree flourishes in alluvial soils, at the foot of hills, and sometimes forms the chief part of the jungle in such situations. The foliage is of a pale green on the upper part, and covered with reddish-brown hairs beneath. The wood is soft, fibrous, spongy, pale in colour, and traversed by longitudinal receptacles or reservoirs filled with the gum, forming ebony-black lines. This gum has many of the properties of india-rubber, but it has also special properties of its own which admit of its being applied to uses for which caoutchouc is not adapted. It possesses the same indestructibility by chemical agents which makes india-rubber so valuable, and it has also the peculiarity of becoming soft and plastic on being plunged into boiling water. In this state it can be moulded into any desired form, which form it permanently retains on cooling. The great convenience and utility of such a substance could not fail to strike the natives of the countries in which it is produced; and accordingly, we find that, long before gutta percha became known to Europeans, it had been fabricated by the Malays into whips, basins, jugs, shoes, &c., thus at length exciting the attention of travellers, and leading to the introduction of some of these articles into Europe under the name of india-rubber, or, earlier still, of mazer-wood.

The honour of having drawn attention to its real nature and uses is due to Drs D'Almeida and W. Montgomerie. The latter, writing from Bengal, remarked on the ordinary name of the plant thus:—"The word is a pure Malayan one—gutta meaning the gum or concrete juice of a plant, and percha the particular tree from which this is procured. The ch is not pronounced hard like k; but like the ch in the English word perch." In 1843 Dr Wm. Montgomerie, of the Indian Medical Service, observing certain Malay knife and kris handles, inquired the nature of the material from which they were made; and from the crude native manufacture inferred at once the extensive uses to which the gutta percha might be put in the arts of Europe. He purchased a quantity of the raw material, sending from Singapore part of it to Bengal, and part to Europe, and suggesting some of the uses to which he thought it might be applied. The quantity sent to England secured to him at once, as the discoverer, the gold medal of the Society of Arts. The surgical uses of gutta percha were early discovered by Dr Oxley of Singapore, who declared it to be "the best and easiest substance ever discovered for the management of fractures, combining ease and comfort to the patient, and very much lessening the trouble of the surgeon."

Gutta percha arrives in lumps or blocks of several pounds' weight, but these often contain impurities, such as stones, earth, &c., introduced by the Malays for the sake of increasing the weight. The purification and preparation of this substance on a large scale are conducted as follows:—The lumps of gutta are subjected to the action of a vertical wheel, on the face of which are fixed three knives which, as the wheel revolves at the rate of 300 revolutions per minute, cut the lumps into thin slices. These are then softened in hot water, and thrown into a rotating machine, where they are further reduced by the action of jagged teeth. From this machine they again fall into water, and are further cleansed. They are then kneaded into a paste in hot water, and rolled between heated cylinders. The mass has now become uniform in texture, and is either rolled out into sheets between steel rollers, or is passed in the mass through heated iron cylinders; after which it is ready for use.

Gutta percha is scarcely affected by boiling alcohol, but it dissolves nearly completely in benzine and in spirit of turpentine with the aid of heat, and also in naphtha, coal-tar, sulphuret of carbon, and in chloroform. Its solution in sulphuret of carbon or in chloroform may be almost entirely deprived of colour by filtering, the process being conducted under a glass jar, in order to prevent loss by evaporation. If this solution be exposed in a flat dish to the air, the solvent will evaporate, leaving a solid cake of white gutta percha, which retains all the properties of the common gutta; and it may be melted by a gradual increase of temperature without acquiring any perceptible colour.

The purposes to which gutta percha is applied are too numerous for recapitulation. Only a few of the more important uses can be here mentioned. It resists the action of water, and is at the same time a bad conductor of electricity; it is therefore employed for inclosing the metallic wires used in the electric telegraph. The efficiency of the submarine telegraph is largely due to this valuable substance.

Various other maritime uses have been found for it in the construction of buoys, life-boat apparatus, &c. Manufacturers and agriculturists have applied gutta percha to use in bands and straps for machinery, tubes, buckets, &c. Architects have accepted its aid in the interior ornamental work of houses, such as cornices, centres for ceilings, &c. Scientific men are aided in their electrical experiments by its high insulating power. Miners, railway officials, and others, find the value of speaking tubes made of this substance; deaf persons are also greatly benefited by its power of conducting sound. Stereotype plates have been made in gutta percha. A mould is taken by pressure of a page of type with woodcutts in gutta percha; from this mould a cast is obtained on a cylinder of gutta percha, and from this last the printing is carried on. The dentist employs gutta percha in fixing or stopping teeth. The chemist is indebted to it in the preservation and conveyance of acids which corrode glass or metallic vessels. It is also extensively used in the manufacture of waterproof clothing, waterproof shoes, &c.

Within the last few years a substitute for gutta percha has been discovered in the juice of the mudlar (Asclepias gigantea), a common plant in India, which also affords a valuable kind of hemp. Care is required in the collection of the milky juice, on account of its exceedingly acrid nature; but when exposed to the air it hardens into a substance closely resembling gutta percha, and having many of its valuable properties. It is, however, unfitted for electrical purposes, for it is found to conduct electricity as freely as a piece of untanned hide.