The Standard specifies the following characteristics of the oil. Appearance: Clear, mobile liquid. Colour: Pale yellow to yellowish brown. Odour: Characteristic, resembling that of citral. Relative density at 20/20 °C: 0,885 - 0,905. Refractive index at 20 °C: 1,4830 - 1,4890. Optical rotation at 20 °C: Range from - 3 to + 1 . Miscibility with 70 % (V/V) ethanol at 20 °C: 1 : 3. Carbonyl value: Minimum 268 (corresponding to 73 % of carbonyl compounds, expressed as citral). Residue from vacuum distillation: Maximum 10 % (m/m).