Eucalyptus Globulus Oil (aromatherapy)

The oil is colorless and quite mobile when rectified. It is pale to dark yellow when old or poorly stored. Rectification or “redistillation” is often carried out on the spot since this operation improves the keeping qualities of the oil. Lower aliphatic aldehydes in the foreruns are partly removed, together with resinified terpenes in the tail fractions; the oil becomes a “Codex” or Pharmacopoeia-quality with a higher Cineole content, and thus easier to export.
Arctander, Steffen . Perfume and Flavor Materials of Natural Origin 

eucalyptus globulus