This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
The anise plant, Pimpinella anisum, contains in all parts, but especially in the seeds, an essential oil, which is obtained by distillation of the seeds with water, the yield being from 1 1/2 to 2 1/2 per cent. From lllicium anisatum, another anise-plant, is by the same process obtained an essential oil, called in commerce oil of illicium or star-anise; the yield being about 2 1/2 to 4 per cent. Both volatile oils are pale yellow, becoming darker by age, and have a sweet aromatic taste and an agreeable aromatic odor, differing somewhat in the two oils. Both oils are entirely neutral to test-paper, are freely soluble in alcohol, and with strong alcohol form clear solutions in all proportions. Spec. grav. 0.970 to 0.990, rising in old oils sometimes to 1.028 (Zeller).
Oil of anise has been met with adulterated with alcohol, camphor, wax, and spermaceti, the last three for the purpose of raising its congealing-point. Anise oil adulterated with alcohol becomes milk-white on being dropped into water. Camphor is detected in the pressed crystalline mass by its odor, the other two by their insolubility in 80 per cent, alcohol. Leonhardi (1878) reports the oil to be sometimes largely adulterated with the stearopten of Russian fennel seed oil, which is detected by the fennel odor developed on heating. - N. D.
The solution in alcohol should not become dark-colored on the addition of a little ferric chloride (phenol, etc.). One drop of anise oil, triturated with sugar and afterward agitated with 'one pint of water, should impart to the latter the pure flavor of anise (absence of other volatile oils). - P. G.