A concrete volatile oil, obtained from the wood of Camphora officinarum. Imported in the crude state from China and Japan, and purified by sublimation in this country.

Characters and test.- White, translucent, tough, and crystalline; has a powerful penetrating odour, and a pungent taste followed by a sensation of cold; floats on water; volatilises slowly at ordinary temperatures; is slightly soluble in water, but readily soluble in rectified spirit and in ether, or when mixed with carbolic acid, chloral-hydrate, or thymol. It can be powdered by being rubbed with a few drops of spirit. Sublimes entirely when heated.

Composition.-Camphor is a solid volatile oil or stearoptene, with the composition C10H16O. Borneo Camphor or Baros Camphor, sometimes substituted for Japanese camphor, has the formula C10H18O, i.e. bears the same relation to Japanese camphor as alcohol to aldehyd.

Impurities.-Borneo camphor, which sinks in water. Fixed salts, left on sublimation. Dose.-1 to 10 gr.

Preparations.

1. Aqua Camphnrae

Aqua Camphnrae. About 1/2 gr. in 1 fl.oz. Dose, 1 to 2 fl.oz.

2. Linimentum Camphorae-1 to 4 of Olive Oil.

3. Linimentum Camphorae Compositum

Linimentum Camphorae Compositum. 1 in 9, with Strong Solution of Ammonia, Spirit, and Oil of Lavender.

4. Spiritus Camphorae

Spiritus Camphorae. 1 in 10. Dose, 10 to 30 min. (in milk or on sugar; an irritant preparation).

5. Tinctura Camphorae Composita

Tinctura Camphorae Composita. "Paregoric Elixir."

Camphor, 30 gr.; Opium, 40 gr.; Benzoic Acid, 40 gr.; Oil of Anise, 1/2 dr.; Proof Spirit, 20 fl.oz. 1 fl.dr. contains 1/4 gr. opium. (See Opium, p. 183.) Dose, 15 to 60 min.

Camphor is also contained in all except four liniments, and in two ointments.

Action And Uses. 1. Immediate Local Action And Uses

Externally.-Camphor closely resembles other aromatic oils in its action, as described under Terebinthinoe Oleum, page 343. It is (1) weakly antiseptic; (2) stimulating to the local circulation; and (3) sedative to the nerves, after preliminary stimulation. The uses of camphor externally depend on these properties: the many liniments and ointments which contain it are intended to increase the nutrition of indurated or stiffened parts, to relieve pain, or to produce counter-irritation. The fluid compounds with carbolic acid, chloral, thymol, etc., are valuable anodynes.

Internally.-Camphor combined with carbolic acid forms an antiseptic and anaesthetic dressing for carious teeth. In the mouth it produces its peculiar taste, increase of the local circulation, salivation, and mucous flow. Reaching the stomach, it causes a sense of warmth; is a weak antiseptic; and again acts like turpentine. Briefly, it is a carminative, its purely local action stimulating digestion and relieving flatulence, and its reflex effects being visible in increased action of the heart, fulness and force of the pulse, and cerebro-spinal excitation. Its carminative properties, whilst generally applicable, are specially valuable in hysterical vomiting.

The intestinal effects of camphor are very similar, and it is therefore useful in some forms of diarrhoea, in the first stage of cholera, and in meteorism.

2. Action On The Blood

Camphor enters the blood freely from the unbroken skin and mucous surfaces, and is found in it unchanged.

3. Specific Action And Uses

In the organs and tissues a portion of the camphor administered is found unchanged; the rest appears to combine with glucose. The nervous system is chiefly affected by this drug, which in doses above those usually ordered may so act on the cerebrum as to produce a kind of intoxication, with confusion of mind, speech, gait, and gesture, and thereupon convulsions, probably originating in the medulla. Moderate doses are said to produce an aphrodisiac, followed by an anaphro-disiac, effect. Camphor has accordingly been used in nervous prostration, especially towards the end of acute specific fevers, such as typhoid; in poisoning by opium and other narcotics; in alcoholism, including delirium tremens; and in various nervous disorders, dependent probably on disturbance of the cerebral and spinal centres, such as insanity, hysteria, whooping cough, chordee or priapism, spermatorrhoea, etc. In large doses of particular preparations, and probably on certain subjects, instead of excitement camphor produces rapid depression, chiefly referable to the heart, namely, failure of the pulse, pallor, coldness and moistness of the surface, impaired local sensibility, and unconsciousness. The respiration is much disturbed after full doses, in association with convulsions and coma. Moderate doses, as we have seen, stimulate the heart reflexly from the stomach. The effect of camphor on metabolism is unknown ; it lowers the body temperature both in health and in pyrexia, an action which may contribute to its value in fevers.

4. Remote Local Action And Uses

Camphor is excreted unchanged by the respiratory organs, on which it probably acts like turpentine, and is a common ingredient of expectorant mixtures, especially as the Compound Tincture. The skin also throws out camphor, which increases and gives its odour to the perspiration, the effect being refrigerant, and probably accounting for the use in common colds of the homoeopathic solution, " spirit of camphor," which is a very powerful preparation, occasionally causing death. The kidneys do not excrete camphor as such, but as a complex product.