Essential oils
Cooling water outlet
Vapours from the still
Practical Action
Cooling water inlet
Condensate out
Figure 4: A simple condenser
Oil separation
The final step in the distillation of essential
oils is the separation from the water flowing
from the condenser using a special flask
called a Florentine. This is a very important
stage as small quantities of oils of very high
value are being handled and maximum
efficiency is the key to profitability.
Most essential oils are lighter than water and
float to the surface of the Florentine. Some
oils, however, are denser than water and
sink to the bottom. For this reason two
types of Florentine are used as shown in
Figure 5. It is common practice to link
several Florentines together. Most of the
oil will separate in the first flask but some
will pass over with the water to the second,
third etc. separates the oil from the water.
This is usually done by letting the mixture
settle in a large container made of glass. If
the oil is heavier than water, the oil is
collected from the bottom of the container,
and if lighter from the top.
If the water is cloudy after separation, it
should be returned to the distillation unit
and redistilled. This is called
'cohabitation'.
Figure 5: Florentines used for oil separation
Using a sequence of
oil separators will
extract a greater
amount of oil.
At the end of the distillation the oil and water in the Florentines is placed in a large laboratory
separating funnel (Figure 6) and allowed stand for several hours after which the water can be run
off. At is stage a small plug of cotton wool is often placed in the outlet of the funnel. As the oil
runs through the plug any final traces of water are removed.
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