An adulteration with nitrobenzole and other volatile oils is recognized by mixing 2 drops of the oil with 100 drops of distilled water, and shaking vigorously. Pure oil must completely dissolve. However, the test yields accurate results only with the use of actually pure distilled water and by accurately observing the above-mentioned proportions. If to 5 cubic centimeters of 90 per cent. alcohol and an equal quantity of distilled water in a test-tube, 10 drops of the oil be added, and, after closing the tube with the finger, mixture be effected by gently turning the tube twice upside down, a clear solution will immediately result if the oil is pure. If, however, it contains nitrobenzole, even only 1 per cent., the latter separates, at first rendering the fluid turbid, but in the course of a minute, when gently agitated, it floats in the form of minute drops upon the fluid, while, when at rest, these drops collect to larger ones on the bottom of the test-tube. If the oil becomes only turbid, adulteration with other volatile oils is indicated. Another test, given by Wagner, is based upon the difference in the specific gravity of mixtures of oil of bitter almonds with oil of mirbane. The specific gravity of commercial oil of bitter almonds varies between 1.040 and 1.043 and that of oil of mirbane between 1.180 and 1.201. 5 c. c. of pure oil of bitter almonds weigh 5.29 grammes. 5 " mixed with ¼ oil of mirbane " 5.39 " 5 " " " ½ " " " 5.57 " 5 " " " ¾ " " " 5.75 " 5 " of pure " " " 5.90 " Oil of bitter almonds is much used in the fabrication of perfumery. In a pure state its odor is by no means agreeable, but rather strong and stupefying. When strongly diluted it is, however, very pleasant. _Angelica oil_ is obtained by distillation with water from the root of _Angelica Archangelica L._, natural order _Umbelliferae_. The oil is lighter than water, possesses the spicy odor of the root and an aromatic pungent taste. It consists mostly of a terpene which turns the plane of polarization to the right, and boils at 320° F. Besides the oil from the root, one obtained from the seeds also occurs in commerce. It is, however, more expensive. In a fresh state it is amber-yellow, and has a specific gravity of 0.8549 at 59° F.; older oil is thickly-fluid, brown, and has a specific gravity of O.9086. It contains a terpene which turns the plane of polarization to the right, and has a lemon-like odor. It is used for fine perfumery.