Bergamot oil may be tested as to its purity by mixing it with alcohol. It becomes pale gray-yellow, forms a sediment which adheres firmly to the vessel and, on shaking, floats about in the form of flakes. After two days the sediment is inconsiderable and difficult to divide into flakes in the clear yellow fluid by shaking. The oil is frequently adulterated with alcohol. To detect such adulteration, Righini recommends the following method: Mix 15 parts of the oil with a like quantity of pure olive oil or oil of sweet almonds. If alcohol is present, it immediately separates, like water, from the fat oil; if no separation takes place the oil is not adulterated with alcohol. The tannin test also gives reliable results. In storing oil of bergamot great care must be exercised to exclude air and light, as it is one of the most changeable oils and soon acquires an odor resembling that of turpentine. Large quantities of oil of bergamot are used in perfumery. It forms, so to say, the basis for most of the finer products. In Cologne water it forms the principal constituent in the mixture of volatile oils. _Cajeput oil_ (_oleum cajeputi_).--This oil is obtained by distillation from the leaves of several species of _Melaleucæ_, natural order _Caryophyllaceæ_, indigenous to the East Indies, Banda, and Malabar. The ordinary oil has a greenish color and possesses a strong odor of camphor and a pungent taste. It is chiefly imported by way of Amsterdam, where it is partially discolored by rectification, so that two kinds, the white and green cajeput oil, are brought into commerce. The color of the latter is generally supposed to be due to a resinous substance containing chlorophyl, though others assert that it originates from the copper of the distilling apparatus and the copper flasks in which it is dispatched. The specific gravity of the oil varies between 0.910 and 0.940, though specifically lighter and heavier oils are said to occur. It is claimed that an artificial cajeput oil is often prepared from camphor and rosemary oil, the green color being obtained by distillation with milfoil. The presence of camphor may be readily determined by thoroughly triturating a few drops of the oil with sugar and then dissolving in water, whereby the particles of camphor separate in the form of white flakes upon the surface. Cajeput oil is frequently adulterated with oil of turpentine and rosemary oil. Such adulteration is recognized by pure cajeput oil dissolving clear in equal parts of 90 per cent. alcohol, which is not the case with the other two oils. _Camomile or chamomile oil_ (_oleum anthemidis_).--Two varieties of oil of camomile are found in commerce, one green and the other blue. The first is derived from the flowers of the genuine or Roman camomile (_Anthemis nobilis_) and the blue from the common variety (_Matricaria chamomila_). The last oil is the one chiefly used in the manufacture of perfumery and in medicine.