OLEUM CACAO.

Botanical Origin—Cacao seeds (from which Cacao Butter is extracted) are furnished by Theobroma Cacao L., and apparently also by Th. leiocarpum Bernoulli, Th. pentagonum Bern., and Th. Salzmannianum Bern.[382] These trees are found in the northern parts of South America and in Central America as far as Mexico, both in a wild state and in cultivation.

History—Cacao seeds were first noticed by Capitan Gonzalo Fernandez de Oviedo y Valdés (1514-1523), who stated[383] that they had been met with by Columbus, being used among the inhabitants of Yucatan instead of money. They were likewise pointed out to Charles V., by Cortes in one of his letters to the Emperor, dated Temixtitan, Sept. 3rd 1526.[384] The tree as well as the seeds and their uses, were at length described by Benzoni,[385] who lived in the new world from 1541 to 1555. Clusius figured the seeds in his “Notæ in Garciæ Aromatum historiam,” Antwerpiæ, 1582.

Cacao butter was prepared and described by Homberg[386] as early as 1695, at which time it appears to have had no particular application, but in 1719 it was recommended by D. de Quelus[387] both for ointments and as an aliment.

An essay published at Tübingen in 1735[388] called attention to it as “novum atque commendatissimum medicamentum.” A little later it is mentioned by Geoffroy[389] who says that it is obtained either by boiling or by expressing the seeds, that it is recommended as the basis of cosmetic pomades and as an application to chapped lips and nipples, and to hæmorrhoids.

Production—Cacao butter is procured for use in pharmacy from the manufacturers of chocolate, who obtain it by pressing the warmed seeds. These in the shelled state yield from 45 to 50 per cent. of oil. The natural seeds consist of about 12 per cent. of shell (testa) and 88 of kernels (cotyledons).

Description—At ordinary temperatures cacao butter is a light yellowish, opaque, dry substance, usually supplied in the form of oblong tablets having somewhat the aspect of white Windsor soap. Though unctuous to touch, it is brittle enough to break into fragments when struck, exhibiting a dull waxy fracture. It has a pleasant odour of chocolate, and melts in the mouth with a bland agreeable taste. Its sp. gr. is 0·961; its fusing point 20° to 30° C.

Examined under the microscope by polarized light, cacao butter is seen to consist of minute crystals. It is dissolved by 20 parts of boiling absolute alcohol, but on cooling separates to such an extent that the liquid retains not more than 1 per cent. in solution. The fat separated after refrigeration is found to have lost most of its chocolate flavour. Litmus is not altered by the hot alcoholic solution.

Cacao butter in small fragments is slowly dissolved by double its weight of benzol in the cold (10° C.), but by keeping partially separates in crystalline warts.

Chemical Composition—The fat under notice is composed, in common with others, of several bodies which by saponification furnish glycerin and fatty acids. Among the latter occurs also oleic acid,[390] contained in that part of the cacao butter which remains dissolved in cold alcohol as above stated. In fact by evaporating that solution a soft fat is obtained. But the chief constituents of cacao butter appear to be stearin, palmitin, and another compound of glycerin containing probably an acid of the same series richer in carbon,—perhaps arachic acid, C₂₀H₄₀O₂, or “theobromic acid” C₆₄H₁₂₈O₂, as suggested in 1877 by Kingzett.

Uses—Cacao butter, which is remarkable for having but little tendency to rancidity, has long been used in continental pharmacy; it was introduced into England a few years ago as a convenient basis for suppositories and pessaries.

Adulteration—The description given of the drug sufficiently indicates the means of ascertaining its purity.