Fig. 3 shows Eucalyptus oil yield as a function of extraction time
in hydro-distillation. As expected, the oil yield increased with
increasing time, from 3.1% at 1 h to 3.8% at 5 h of extraction, indicating
a rapid extraction rate in the first 1 h. This is probably
because the Eucalyptus leaves grinding process liberated the essential
oil onto the surface of the plant particles [14], allowing more
ready extraction by the water vapour. Therefore, most of oil was
extracted during the first hour [14].