1911 Encyclopædia Britannica/Cloves
CLOVES, the dried, unexpanded flower-buds of Eugenia caryophyllata, a tree belonging to the natural order Myrtaceae. They are so named from the French word clou, on account of their resemblance to a nail. The clove tree is a beautiful evergreen which grows to a height of from 30 to 40 ft., having large oval leaves and crimson flowers in numerous groups of terminal clusters. The flower-buds are at first of a pale colour and gradually become green, after which they develop into a bright red, when they are ready for collecting. Cloves are rather more than half an inch in length, and consist of a long cylindrical calyx, terminating in four spreading sepals, and four unopened petals which form a small ball in the centre. The tree is a native of the small group of islands in the Indian Archipelago called the Moluccas, or Spice Islands; but it was long cultivated by the Dutch in Amboyna and two or three small neighbouring islands. Cloves were one of the principal Oriental spices that early excited the cupidity of Western commercial communities, having been the basis of a rich and lucrative trade from an early part of the Christian era. The Portuguese, by doubling the Cape of Good Hope, obtained possession of the principal portion of the clove trade, which they continued to hold for nearly a century, when, in 1605, they were expelled from the Moluccas by the Dutch. That power exerted great and inhuman efforts to obtain a complete monopoly of the trade, attempting to extirpate all the clove trees growing in their native islands, and to concentrate the whole production in the Amboyna Islands. With great difficulty the French succeeded in introducing the clove tree into Mauritius in the year 1770; subsequently the cultivation was introduced into Guiana, Brazil, most of the West Indian Islands and Zanzibar. The chief commercial sources of supply are now Zanzibar and its neighbouring island Pemba on the East African coast, and Amboyna. Cloves are also grown in Java, Sumatra, Réunion, Guiana and the West India Islands.
Cloves as they come into the market have a deep brown colour, a powerfully fragrant odour, and a taste too hot and acrid to be pleasant. When pressed with the nail they exude a volatile oil with which they are charged to the unusual proportion of about 18%. The oil is obtained as a commercial product by submitting the cloves with water to repeated distillation. It is, when new and properly prepared, a pale yellow or almost colourless fluid, becoming after some time of a brown colour; and it possesses the odour and taste peculiar to cloves. The essential oil of cloves—the Oleum Caryophylli of the British Pharmacopoeia—is a mixture of two substances, one of which is oxidized, whilst the other is not. Eugenol, or eugenic acid, C10H12O2, is the chief constituent. It is capable of forming definite salts. The other constituent is a hydrocarbon C15H24, of which the distilling point differs from that of eugenol, and which solidifies only with intense cold. Oil of cloves is readily soluble in alcohol and ether, and has a specific gravity of about 1.055. Its dose is ½-3 minims. Besides this oil, cloves also contain two neutral bodies, eugenin and caryophyllin, the latter of which is an isomer of camphor. They are of no practical importance. The British Pharmacopoeia contains an infusion of cloves (Infusum Caryophylli), of which the strength is 1 part in 40 of boiling water and the dose ½–1 oz. Cloves are employed principally as a condiment in culinary operations, in confectionery, and in the preparation of liqueurs. In medicine they are tonic and carminative, but they are little used except as adjuncts to other substances on account of their flavour, or with purgatives to prevent nausea and griping. The essential oil forms a convenient medium for using cloves for flavouring purposes, it possesses the medicinal properties characteristic of a volatile oil, and it is frequently employed to relieve toothache. Oil of cloves is regarded by many dental surgeons as the most effective local anaesthetic they possess in cases where it is desired, before cutting a sensitive tooth for the purpose of filling it, to lower the sensibility of the dentine. For this purpose the cavity must be exposed to cotton wool saturated with the oil for about ten days.