Camphor is a solid essential oil which is found in many plants, and may be separated from many essential oils. It particularly abounds in certain species of Lauraceæ (q.v.). The principal source of the camphor of commerce is the Camphor Laurel (Cinnamomum (Laurus) Camphora), a tree of China, Japan, Formosa, and Cochin-China, and which has been introduced into Java and the West Indies. Camphor is chiefly imported in the crude or unrefined state from Formosa and Japan, where the wood is cut into chips and distilled with water, the vapour of camphor rising with the steam being collected in the head of the still. After collection camphor oil drains off, which is used in China for rheumatism. In the refining process the grains of impure camphor are detached, and being introduced, along with a small proportion of quicklime, into a large globular glass vessel in quantities of about 10 lb., are reheated, when first the water rises in steam, and is allowed to escape at a small aperture; and thereafter, this aperture being closed, the camphor sublimes and resolidifies in the interior upper part of the flask as a semi-transparent cake, leaving all the impurities behind. The flasks are then cooled and broken by throwing cold water on them, and the camphor taken out and sent into market. The glass globes employed are called by an Italian name, bombolo, the sublimation of camphor having been first practised in Venice. Camphor has also of recent years been sent into the market sublimed in almost powdery crystals, as 'flowers of camphor,' a very convenient form for pharmaceutical purposes.—Camphor was unknown to the Greeks and Romans, but has been highly valued since ancient times in the East, and was first brought to Europe by the Arabs. It is a white tough solid, slightly lighter than water, and having the formula . It is very sparingly soluble in water, but freely soluble in alcohol, ether, acetic acid, and the essential oils. It fuses at ( C.), and boils at ( C.), but volatilises somewhat rapidly at ordinary temperatures. When set fire to, it burns with a white smoky flame. Thrown upon water, it floats, and may be set fire to, when the currents generated alike from the gradual solution of the camphor in the water and the irregular burning of the pieces, cause a curious rotatory motion. It has a peculiar hot aromatic taste, and an agreeable characteristic odour.
Camphor is used alike in European and oriental medicine, both internally and externally, as a temporary stimulant. It is frequently employed in gout and rheumatism. In small doses it acts as an anodyne and antispasmodic; in very large doses it is an irritant poison. It is generally reckoned an anaphrodisiac, although some maintain that it has an opposite action. Its alcoholic solution, and liniments in which it is the principal ingredient, are much used for external application in sprains and bruises, chilblains, chronic rheumatism, and paralysis. The odour of camphor is very noxious to insects, and it is therefore much used for preserving natural history specimens, and its fumes have been from early times regarded as of antiseptic value, an opinion confirmed by bacteriology.
Once obtained from Sumatra, Borneo, and inland China, the Camphor of commerce is now only got from Japan and Formosa (the latter not so good). Borneo or Sumatra Camphor is the produce of Dryobalanops aromatica, a large tree of the order Dipterocarpeæ. The camphor is obtained by cutting down the tree, and splitting it into small pieces, being found in crystalline masses in natural cavities of the wood. To this substance the Chinese ascribe extraordinary medicinal virtues, so that it is sold among them at sometimes more than fifty times the price of common camphor. Hence, although the form of camphor earliest known, it no longer appears in European commerce. Its composition is , and it can be converted into common camphor by the action of nitric acid. The same tree also yields a 'camphor oil' isomeric with oil of turpentine, . This is collected by tapping or felling the tree. A third variety, Ngai, or Blumea Camphor, of intermediate but still high value, is manufactured at Canton from Blumea balsamifera, a tall herbaceous composite. Its chemical composition is identical with the last. It is consumed in Chinese medicine, and in perfuming the finer sorts of Indian ink. Similar crystalline bodies separate from the oils of bergamot, neroli, thyme, buchu, sassafras, &c., but are of no special importance.