Cetaceum, B.P. Spermaceti.
CETACEUM, B.P.
SPERMACETI.
Related entry: Sperm oil
Spermaceti is a concrete fatty substance obtained from the head of the sperm whale, Physeter macrocephalus, Linn. (Order Cetacea), which inhabits the Pacific, Atlantic, and Indian Oceans. It is also official in the U.S.P. The sperm oil, found in a large cavity in the animal's head, deposits on standing a crystalline substance, which is separated by filtration, pressed, melted, purified from traces of oil with diluted sodium hydroxide solution, and finally freed from the soap thus produced, and from excess of alkali. Spermaceti occurs in translucent, crystalline, pearly-white masses, unctuous to the touch, with little odour or taste. It may be powdered by the aid of a little alcohol, or almond or olive oil. Specific gravity, 0.94 to 0.95 (0.935 to 0.944 at 25°, and 0.842 at 100°). Melting-point, from 46° to 50° (U.S.P., 42° to 50°). It is readily inflammable, and burns with a bright, somewhat sooty flame. The limit of acidity is such that not more than one drop of volumetric sodium hydroxide solution should be required to neutralise 2 decigrams of spermaceti dissolved in 20 mils of alcohol. Saponification number 125 to 135. The crystalline appearance of spermaceti, its solubility in boiling alcohol, and its very low acidity are good indicators of its purity. Adulteration with stearic or other fatty acid may be detected by rise in the acid number or by adding water to the filtrate from the cooled solution in alcohol, when a precipitate will be obtained if stearic or palmitic acid be present, or by boiling 1 gramme with 1 gramme of anhydrous sodium carbonate and 50 mils of alcohol, filtering and acidifying the filtrate with acetic acid, when a precipitate should not be formed. Paraffin is insoluble in boiling alcohol.
Insoluble in water and cold alcohol, but soluble in ether, chloroform, carbon bisulphide, fixed and volatile oils, and boiling alcohol, being almost entirely deposited from the latter solvent on cooling.
Constituents.—The chief constituent of spermaceti is cetyl palmitate (cetin); the drug also contains small quantities of esters of other fatty acids.
Action and Uses.—Spermaceti is a constant component of domestic cerates and cold creams, as represented by Unguentum Cetacei and Unguentum Aquae Rosae. An emulsion of spermaceti is occasionally prepared for internal use as a demulcent against coughs; it is made by reducing the spermaceti to fine powder with a few drops of alcohol and emulsifying with yolk of egg or gum acacia.
Dose.—½ to 2 grammes (8 to 30 grains).
PREPARATION.
- Unguentum Cetacei, B.P.—SPERMACETI OINTMENT.
- Spermaceti, 20; white beeswax, 8; almond oil, by weight, 72; benzoin, in coarse powder, 2. Add the benzoin to the previously melted spermaceti, beeswax, and almond oil, and heat gently for two hours, stirring frequently; then strain, and stir until cold. This ointment is used as an emollient and as a basis for the application of other drugs to the skin. Applied on lint, it is a cooling dressing for blisters which have been produced by friction or the application of counter-irritants. Because of the presence of benzoin, spermaceti ointment is not suitable as a basis for eye ointments. Unguentum Cetacei of foreign pharmacopoeias is prepared without benzoin; it is then a very bland and soothing ointment, but should be freshly prepared.
