384 THE CHEMISTKY OF ESSENTIAL OILS
" Not only has there been an increase in the total amount of leaves-
reaped from the plot, but also an increase in the proportion of oil
obtained from the leaves, which in 1912, on the average, was 16
*
7 oz.,
and in 1913 18*3 oz. per 100 Ib. of leaves as reaped.Date of Distillation.January 3rd.
January 31st
March 3rd
April 1st
May 1st.
May 6th
June 12bh
June 26th
July 16th
August 22nd
September 26th
October 31st.
November 28th
December 15thAmount of
Fresh Leaves.165
162
162
185
153
180
160
176
188
160
174
195
163
104
Yield of Oil,
c.c.764
773
732
931
783
909
905
1115
1149
814
846
801
830
639
Ounces per
100 Ib.
Fresh Leaves.16-5
16
16
18
18
18
20
22-7
21-8
18
17-4
14-7
18-1
21-7
Specific
Gravity.•9410
•9496
•9806
•9443
•9620
•9515
•9288
•9714
•9520
•9421
•9219
•9274
•9242
•9491
Phenol-
content,
per Cent.50
54
70
58
63
60
47
66
60
53
45
51
48
62
" The particular object of making reapings monthly was to decide
if at any season of the year the leaves yielded a higher percentage of
oil or an oil of better quality; the data collected from the reapings made
•in 1913 are shown in the preceding table.
"In considering these results it is noticed that there are abrupt
differences in certain months, e.g. the high specific gravity and phenol-
content in March, the low phenol-content on 12 June, and the striking
fall in the proportion of oil obtained in October, that need explanation ;
but, on the whole, the results are in accord with those obtained in the
previous year, when June and July gave better returns than any two
contiguous months of the year.
" Experiments both here and in Antigua have shown that specific
gravity and phenol-content are considerably influenced by the kind of
leaves collected for distillation, and the larger the amount of immature
growth included in the reapings the less satisfactory these two factors
prove to be. This is again clearly demonstrated in two tests made for
the purpose, the first on 15th December, 1913, when only mature leaves
were distilled. The specific gravity and phenol-content in this case
were as shown in the table, and in the test for comparison made on
16th January, 1914, young growth preponderated, and the specific gravity
of the oil was O8856 and the phenol-content only 33 per cent. In view
of this it is premature to say whether the rise in yield and the better
quality of the oil obtained in the middle of the year during the last two
years are due solely to the absence of young growth at the time. For
the first six months of 1914 the average \yield per 100 Ib. of leaves has
risen to 20 oz. It has been a rule-of-thumb practice to dry the leaves
for three days before distillation, but no scientific examination of thia
point has been carried out, and it is not known whether the drying in-
creases or diminishes the oil yield."