322 THE CHEMISTEY OF ESSENTIAL OILS
- The percentage of volatile oil in the " tears" of asafoetida may
equal that in the " mass " variety, or even be slightly higher in good
specimens, but in general it is slightly lower. - In both varieties the actual percentage of volatile oil present is
12 to 16 per cent.
The "tears" themselves, however,and the tinctures prepared from
them are far more pungent in their odour than the " mass " and tinc-
tures from it, despite this approximate equality in the percentage of oil
present. It appeared, therefore, that notwithstanding the greater pro-
portion of oil in the mass the composition of it might be different, and
needed further investigation. They found the following amounts of
sulphur in the two oils :—
Sulphur in oil from mass = 2*06 per cent.
„ „ tears = 10-44 „
It would appear, therefore, that the oil of the mass differs in com-
position from the oil of the tears in containing a far lower proportion
of sulphur compounds, and is certainly less offensive in smell.
Harrison and Selfl have examined a number of samples of this oil,
distilled by themselves from the drug as found on the London market,
with the following results :—
No.1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
Percentage
of Oil.11-0
16-4
9-4
5-8
10-1
7-2
11-1
15-7
9-6
7-3
14-1
16-7
11-9
14-1
17-1
Sp. Gr. of Oil
at 15'5°.0-976
0-975
0-917
0-981
0-915
0-993
0-918
0-920
0-925
0-957
0-923
0-927
0-930
0-930
0-929
Ref. Index
of Oil at 20°.1-5200
1-5152
1-4952
1-5207
1-4942
1-5250
1-4980
1-4978
1-4993
1-5077
1-4985
1-4982
1-4997
1-4987
1-4999
Rotation
of Oil.- 10° 16'
- 9°0'
+ 6° 58'
- 9° 30'
+ 9° 39'
- 35° 55'
+ 0°50'
+ 5° 40'
+ 4° 32'
- 17° 3'
—
Percentage
of Sulphur
in Oil.28-2
21-6
19-3
29-2
17-6
37-8
20-8
19-7
21-6
19-9
—
The sulphur in the oils was determined in the following manner:
About 0
- 5 grm. of the oil was weighed out into a 150 c.c. flask, fitted
by a ground neck to a vertical condenser; 5 c.c. of water was then
added through the tube, followed by 5 c.c. of HNO 3 , and if necessary
the flask was gently warmed to start reaction, which then proceeds
somewhat vigorously; 3 grms. of KBr in powder was then dropped in
through the condenser tube, and the liquid boiled for ten minutes, after
. Jour. (1912), [4], 34, 205.