This method is also called Supercritical CO2 Extraction. The fluid state of Carbon Dioxide is what is referred to when the term 'supercritical' is used. Compared to steam distillation in which heated water/steam is used as the solvent, in CO2 extraction the liquid form of carbon dioxide (supercritical CO2) is used as the solvent. This extraction method pulls not only oils but substances such as pigments and resin from the plant matter. None of the constituents of the resulting oil are damaged by heat, and CO2 extracts often give off more of the aroma of the natural herb, spice, or plant than a steam or water distilled essential oil. Essential oils obtained using the CO2 extraction method have been said to contain more plant constituents than essential oils extracted using steam distillation.