The Standard specifies the following characteristics of the oil. Appearance: Clear, mobile liquid. Colour: Pale yellow to orange-yellow. Odour: Characteristic with a strong note of citral. Relative density at 20/20 °C: 0,872 - 0,897. Refractive index at 20 °C: 1,4830 - 1,4890. Optical rotation at 20 °C: Range from - 3 to + 1 . Carbonyl compounds content, expressed as citral: Minimum 75 %. Solubility in ethanol at 20 °C: Freshly distilled oils are soluble in 70 % (V/V) ethanol.