In commerce two principal varieties are distinguished: Siberian or Russian and Canadian, English or American castor, the first being the most valuable. The length of a Siberian sac varies between 2.36 and 4.72 inches, the width between 0.98 and 2.55 inches, and the thickness between 0.78 and 1.57 inches; it weighs from 1.76 to 8.81 ozs. One of the sacs is generally somewhat smaller than the other. The exterior skin of the sac is almost smooth and, in a dry state, dark brown; the interior is dirty yellow, intermixed with a dense cellular tissue, which envelops the castor-substance and is grown together with it. In a dried state, the latter is dark brown, without lustre, almost friable, of a very strong, peculiar odor, and a pungent, somewhat bitter, aromatic taste.
The sacs of Canadian castor are smaller than the Siberian, they being at the utmost 3.15 inches long, 0.98 inch thick, and darker and uneven. The interior mass is resinous, hard, with a lustrous fracture, red-brown, and can be readily pulverized. The odor is weaker, somewhat musty and ammoniacal, and the taste more bitter and less pungent than that of the Siberian castor.
Castor is much adulterated—pebbles, pieces of lead, dried blood, etc., being frequently found in the sacs. These frauds can generally be detected in cutting the sac open. Spurious sacs are said to be frequently found among the genuine sacs of Canadian castor. These spurious sacs are prepared by drying a mixture of castor, resin, dragons' blood, etc., in the scrotum of goats.
In perfumery, castor is now very seldom used, the perfumers preferring musk and civet, which, certainly, give a somewhat different scent.
Ambergris is a fatty, waxy substance, often found floating on the sea on the coasts of Arabia, Madagascar, Japan, etc. It is also found in the cæcum of the sperm whale (Physetus macrocephalus, Schow), and is supposed by some to be a morbid secretion in the urinary bladder. According to Mr. Beale, it merely consists of the indurated fæces of the animal, perhaps somewhat altered by disease. It has a gray-white color, often with a black streak and a slight agreeable odor, like that of benzoin, which becomes more pronounced on heating. When held for some time in the hand it becomes soft and flexible. It melts at the temperature of boiling water, and, when more strongly heated, volatilizes in the form of a white vapor, leaving but slight traces of ash behind. Its specific gravity is 0.8 to 0.9. It is insoluble in water, sparingly soluble in cold spirit of wine, and more readily so in hot spirit of wine, ether and volatile and fat oils. It is almost completely soluble in absolute alcohol. Though ambergris crumbles readily, it can only with difficulty be converted into coarse powder. With the finger it can be polished like hard soda-soap.
The principal constituent of ambergris is ambrin or ambrein, a non-saponifiable fat, which, from a saturated alcoholic solution of ambergris, crystallizes, after standing for some time, in the form of verrucose, whitish or lustrous acicular crystals. According to John, ambergris consists of 85 per cent. ambrin, 12.5 per cent. sweet balsamic extract, further benzoic acid, sodium chloride, and 1.5 per cent. insoluble brown residue. When distilled with water, ambergris yields 13 per cent. of a volatile oil having an agreeable odor. A red-hot iron wire readily penetrates ambergris, and from the hole thus made flows an oily liquid of a strong and agreeable odor.
On account of its high price, ambergris is frequently adulterated, the commercial article being often nothing but an artificial mixture of benzoin, olibanum, wax, and flour, with other substances, perfumed with musk. Such adulterations are detected by the appearance, proportions of solubility, nature of the fracture and the content of ash. A small quantity of pure ambergris, exposed to heat, melts without forming bubbles or scum. It is easily punctured with a heated needle, which, when withdrawn, should come out clean and without anything adhering to it, and the characteristic odor of ambergris should be immediately evolved. The surface should be rugged, that with a smooth and uniform surface being generally factitious.
In perfumery, ambergris is not so much used on account of its agreeable odor, but rather to make the perfumes more constant.