392 THE CHEMISTEY OF ESSENTIAL OILS
morning just before sunrise, and the picking continues till ten or eleven
o'clock, or on cloudy days during the whole day, as it is important that
the roses should not be picked when the sun's heat is on them. A
garden of an acre when well planted will yield about 100 Ib. of flowers
every day for three weeks. The roses are carried to the distilleries,
which are very numerous, and distilled as quickly as possible. How-
ever, if the flowers come in too quickly, they are sometimes left for
twenty-four hours before being distilled, the resulting oil being thereby
impaired in value. The distilleries are primitive buildings, sometimes
little better than wooden sheds. On one side the stills are kept in rows.
These are copper alembics about 3 to 5 ft. in height, resting on a fur-
nace built of bricks. The average content of each still is about 20 gal-
lons, the charge usually being 10 kilos of flowers and 75 litres of water.
The condenser is a straight or worm tube passing through a vat of
water, into which cold water continually runs. A brisk fire is kept up
for an hour to an hour and a half, and when 10 litres of liquid are ob-
tained the fire is drawn. At times 15 litres are distilled over, but the
result is an otto containing a larger amount of stearoptene. The still
is then opened and the spent petals, or rather flowers, for the green
FIG. 34 .-A, copper alembic ; B, condenser; C, receiver.plants are seldom separated, are thrown away, and the residual hot
water is returned to the still with cold water to make up the 75 litres,
with a fresh charge of flowers. This operation is repeated until, as a
rule, 40 litres of rose water have been collected. These 40 litres are
now distilled, and the first 5 litres are collected in a long-necked flask.
The residual 35 litres are used ,for distilling fresh flowers. The 5 litres
distilling over are cloudy, and the oil drops gradually rise and collect
in the neck of the flask. When it has all risen, it is removed by a
small tin funnel with a tiny orifice for the water to be drawn off. The
yield is variable, a warm humid spring with intervals of strong sun-
shine being more favourable than an uninterrupted hot dry season. The
average yield in Bulgaria is about 1 kilo of otto from 3000 kilos of rose
leaves.
Adulteration of Bulgarian otto of rose is so common as to render it
a matter of the highest importance to purchase this expensive product
from dealers of repute, as the adulteration practised has been raised to>