84 THE CHEMISTBY OF ESSENTIAL OILS
states that an earthern garrah was in use in the distillery visited by
him. It is placed in "running water or in default of running water into
a pond, with the lower end of the condensing tube leading to it. The
capacity of the condenser varies according to the size of the still and is
capable of holding anything from 8 to 15 gallons.
The still is charged with grass and cold water in proportions of one
to four by weight. The fire is then put under the still and the distillate
commences to come over within three-quarters to one and a half hours,
according to the capacity of the still and the size of the grate.
The yield of oil may be as low as 0
- 15 per cent, in the case of care-
lessly dried material, or as high as 1 per cent, if the material is care-
fully dried.
Experiments on the steam distillation of the oil carried out by
Messrs. Pheroze & Co. of Bombay resulted in a yield of O87 per cent,
of oil by steam-distilling the entire plant, which consisted of 54 per
cent, of stalks, 28*5 per cent, of leaves, and 17'5 per cent, of flower-
heads. Each portion of the plant when distilled separately gave the
following figures:—
Stalks '04 per cent, of essential oil.
Leaves 1-32
Flower-heads 1-71 „ ,, „
They remark that the yield might have been much more, say 1 per
cent, to 1*25 per cent., had the distillation been carried out with abso-
lutely fresh grass immediately after it was cut, instead of with grass
which must have lost some of its volatile oil during transit to Bombay.
Pheroze & Co. did not report the percentage of moisture in the grass
at the time of distillation. In the fresh green grass, the moisture is
usually about 60 per cent., so that, assuming the moisture in the grass
distilled by Pheroze & Co. to have been 50 per cent., the yield of oil
calculated on completely dry grass works out to 1'74 per cent, on the
entire plant and 2*94 per cent, of oil on flower-heads and leaves only,
neglecting the traces of oil in the stalks.
Experiments carried out with air-dried " Sofia" grass, obtained
from the Melghat Division of the Central Provinces, and containing
13 per cent, of moisture, gave 0*41 per cent, of oil by steam distillation.
The entire plant consisted of 60 per cent, of flower-heads and leaves and
40 per cent, of stalks, so that, calculated on the completely dried flower-
heads and leaves only, the percentage of oil obtained comes to 0*78 per
cent. The yield of oil on the entire plant of " Motia " grass containing
12*88 per cent, of moisture, was 0'5 per cent. The entire plant con-
sisted of 40 per cent, of flower-heads and leaves and 60 per cent, of
stalks. Leaving out of consideration the stalks, the yield comes to-
1-42 per cent, calculated on the completely dried flower-heads and
leaves only. It may be noted here that the grass distilled was dry and
over-ripe, while most of the flower-heads had been damaged in transit..
The percentage, therefore, cannot be compared with that obtained by
Pheroze & Co. The above results obtained by the distillation of dry
grass have only been mentioned to show that by steam distillation not
only can the green grass be worked in October and November, but that
the air-dried grass containing about half the amount of oil as compared
with fresh grass can be kept in stock for running the still after the crop
has been reaped.
Palmarosa oil is a pale yellow liquid (sometimes rather dark on ac-