Camphor, the name given to different concrete volatile products, commonly obtained by distillation from the chipped wood, roots, and leaves of certain aromatic plants, and condensed by sublimation into a solid form. As known in commerce, camphor is procured only from Japan and the islands of Formosa, Sumatra, and Borneo; but one species of the trees which produce it is said to abound in some parts of China. In Sumatra and Borneo the product is limited to a narrow range between the equator and lat. 3° N. Two kinds are known in commerce, the consumption of one of which is monopolized by the Chinese, who, by a mere whim, set a value upon it from 70 to 100 times the price of the other variety. The kind they so highly esteem is the Malay article, the product of a gigantic tree, dryobalonops camphora or aromatica, which grows wild on the slopes of the Diri mountains in Sumatra, and in the territories of the sultanate of Brunai in Borneo, which attains a height of more than 100 ft., and a diameter of 6 or 7 ft. Siebold describes one which measured 50 ft. in circumference. The camphor is obtained from this tree without employing the process of separation required in procuring the other variety.
It is found in concrete masses secreted in longitudinal fissures and crevices in the heart wood, and is extracted by splitting the trunk in pieces and picking out the lumps with a pointed instrument or the nail, when they are small. Some lumps have been found as large as a man's arm, but the product of a large tree does not often reach 20 lbs.; half this amount is a good yield for a middling-sized tree, and in hunting for one many are felled and split up with great labor that furnish no camphor; hence the high price of the article. The Chinese, it is said, pay for it at the rate of $1,000 to $1,200 the picul (133 lbs.), or for a very superior quality even $3,000 for 1 cwt.; while the Japan article obtained in their ports, and hence known as Chinese camphor,, is worth only from $12 to $15 the picul. The camphor-wood trunks are supposed to be made of the wood of this tree. It answers well for house and ship timbers and articles of furniture, especially such as are intended to contain and preserve clothes. It is very easy to work, splits readily, and is never attacked by the many destructive insects of the East, which will so speedily devour any European woods, and even those of the East, except the teak, the calambuco, and the camphor.
The young trees produce, instead of the full-formed camphor, a straw-colored fluid, which is called in the East Indies the oil of camphor, and is used as an external application in rheumatic complaints. This is supposed by Dr. Thompson to be the same substance as the solid product, the composition of which he represents by the formula C10H9O. But the genuine oil of camphor he describes as the product of the same trees which furnish the camphor of European commerce. This is known in this country and in Europe as the camphor of Japan or common camphor; and of this two varieties are recognized in commerce: one, the Dutch, Japan, or tub camphor; and the other, the Chinese or Formosa camphor. The latter is principally produced in the island of Formosa, and thence carried in junks to Canton. There it is packed in square chests lined with lead, and distributed to the various eastern ports at which we obtain it. It is a crude article in dirty gray grains, agglutinated together in lumps, and contaminated with many impurities. The tub camphor is obtained in Batavia, whence it is exported in tubs securely covered with matting, and an outside tub, and containing 100 lbs. or more.
This is in pinkish-colored grains, coarser and purer in general than the Chinese. Both varieties are probably obtained from the same tree, the laurus cam-phora of Linnaaus, or camphora officinarum of Nees von Esenbeck, an evergreen of considerable size, resembling the linden tree, and bearing a red berry like that of the cinnamon. All parts of the plant possess the odor of camphor, and produce this article when cut into small pieces and distilled. The process is conducted in large kettles of iron, which are furnished with covers in the form of a dome, in which stalks of rice or grain are placed for receiving the camphor sublimations. But little water is used, and only a moderate heat applied to volatilize this and the camphor together. The latter condenses upon the straw. - All the camphor of commerce is a crude article, which requires purification before it is fit for use. The art of refining it was long monopolized in Europe by the Venetians, and afterward by the Dutch; and it is not long that we have in this country been independent of the latter for our supplies of the pure material.
The crude article is introduced together with about 1/50 the quantity of quicklime into vessels of cast iron, which serve as retorts, and over which are placed covers of sheet iron connected with the lower vessels by a small aperture. A number of these stills are placed in a large sand bath, and, after the melting of the camphor within them, kept at a uniform temperature, that the process may go on quietly. The quicklime serves to retain the moisture, which would otherwise interfere with the condensation of the pure camphor. This takes place under the shelf upon which the cone stands, the vapor when in excess passing into the loosely affixed cones of sheet iron, care being taken to keep the hole open. The deposit of camphor is in the form of a circular cake an inch or two thick, with a hole through the centre. - The composition of camphor is represented by the formula C10H8O. Its specific gravity is 0.987; its melting point is 288° F.; and it boils at 400°. It is a semi-transparent white substance, crystallizing in hexagonal plates, and with a crystalline fracture; soft, friable, and tough, so that it is.diffi-cult to reduce it to powder. When moistened with a few drops of alcohol, it is easily pulverized.
Its taste is somewhat bitter and pungent, attended with a slight feeling of coldness; its odor is strong and fragrant, highly penetrating, and exceedingly noxious to troublesome insects. Exposed to the air, it soon disappears in vapor; in close vessels it sublimes and crystallizes upon the parts most exposed to the light. It is readily inflamed, and burns with much smoke and light. A singular effect is noticed on dropping small pieces of clean camphor upon the surface of pure water. The particles rotate and move rapidly about, sometimes for several hours. Any greasy matter touching the water will at once put a stop to the motions. This phenomenon has been shown to be due to the giving out of a thin film of camphor upon the surface of the water, and the consequent reaction upon the fragment which is its source. Mr. Tomlinson states that he has found the same phenomenon in the raspings of cork steeped in sulphuric ether, in sublimated benzoic acid, potassium, etc. - Camphor is readily dissolved in alcohol, this taking up about its own weight of it; indeed, 100 parts, of sp. gr. 0.806, dissolve 120 of camphor, forming the camphorated spirit of the pharmacopeias. Water added to the solution precipitates the camphor in fine powder.
It is soluble in water only to the extent of about 1 part in 1,000. Chloroform is a powerful solvent of it. - In medicine camphor is made use of internally and externally. In small doses it increases the activity of the heart, stimulates the cerebral functions, and may produce transient giddiness and headache. In larger doses it at first diminishes and then increases the rapidity of the pulse, the giddiness is much increased, while delirium and convulsions as well as partial loss of consciousness have been observed. The effects are usually not of long duration, and some observers have taken considerable doses (Trousseau, 35 grains) with much slighter effects then those described. Fatal poisoning, death taking place by coma, is said to have occurred in one case, a girl, from ten grains. Camphor is used as a nervous stimulant in low forms of fever, also in diarrhoea, cholera, and catarrh. The tincture is used as a domestic remedy in headache and other nervous affections. It has some reputation as a sedative to the genital organs.
Dissolved in olive oil, or as recently proposed in chloroform, it forms an excellent liniment.