According to experiments by Schimmel & Co., pure citronella oil must give a clear solution, when 1 part of the oil is vigorously shaken with 10 parts of 80 per cent. alcohol. If, in executing the test, the kind of turbidity is observed, and whether the portion insoluble in alcohol separates, after standing, upon the surface or on the bottom of the fluid, and further, if the above-mentioned quantity of alcohol is not added at one time, but at first only 1 or 2 parts of it, a conclusion may be drawn as to the kind and quantity of the adulterant. Petroleum causes a milky-white turbidity, while in the presence of fat oil the mixture becomes turbid, but not actually milky. As a rule, fat oil deposits, after standing, on the bottom, while petroleum floats upon the surface of the fluid. Citronella oil adulterated with fat oil does not dissolve in 1 to 2 parts nor in 10 parts of 80 per cent. alcohol, while oil adulterated with not too large a quantity of petroleum, gives a clear solution with 1 to 2 parts. The determination of the specific gravity may also serve for the detection of adulterations. This holds good, however, only for petroleum, which reduces the specific gravity, an addition of fat oil producing no deviation in this respect. The specific gravity of the oil should not be below 0.895 at 59° F. Citronella oil is much used for perfuming cheap hair oils and toilet soaps; it is the chief constituent of all perfumes for honey-soaps. In the American soap industry it is extensively used, the yearly consumption being estimated at 1½ million ounces. _Cloves, oil of_ (_oleum caryophylli_), is obtained by distillation with steam, or by extraction from the cloves of commerce, which are the dried unexpanded flower buds of _Caryophyllus aromaticus, L._, or the clove tree. Oil of cloves, when fresh, is almost colorless, but on exposure to air acquires a brownish coloration and a thickly fluid consistency. It has the aromatic taste and odor of cloves, and a specific gravity of 1.300 to 1.065. It frequently shows a slightly acid reaction, boils at 482° F., and congeals at 4° F. It is readily soluble in alcohol, ether, and strong acetic acid. It consists of a terpene (C_{10}H_{16}) and eugenol (C_{10}H_{12}O_{2}), the odor of the oil being due to the latter. The terpene has a specific gravity of 0.918, and in distilling passes over first (light oil of cloves). The eugenol, when fresh, is colorless, has the odor and taste of cloves, a specific gravity of 1.063 at 65° F., boils at 487.4° F., is insoluble in water and glycerin, but soluble in alcohol, ether and glacial acetic acid. Its alcoholic solution is colored magnificently blue by ferric chloride. If in an alkaline solution it is oxidized with potassium permanganate, vanillin being formed. An inferior quality of oil is obtained from the stems of the clove buds. It dissolves with greater difficulty than the oil prepared from the buds, and has a darker red-brown color.