Chemistry of Essential Oils

474 THE CHEMISTEY OF ESSENTIAL OILS.

No. Pressure. Temperature. Per Cent. i Optical Rotation, Remarks.

1 2 3 4 5 6 7

10 mm.

10 „

10 „

14 „

14 „

14 „

14 „

60 to 86°

(^86 9)
(^90 9)
(^95 9)
(^97 1)
(^100 1)
(^110 1)
, 90°
, 91°
, 97°
, 100°
, 110°
, 120°
4-5
9-0 '
15-0 '
51-0
5-0
3-0
3-0
ad + 5° 24'
'ad + 8° 50'
a,, + 11° 21'

• 0£ + 11° 15'
  cw + 8°
  ad - 11°
  ad - 18° 20'

lina]ol

fraction

The oil is sometimes adulterated with fatty oils, which raise the

specific gravity, yield a high ester value, and are not volatilized on a water-

bath.

Shiu oil, an oil distilled in Central Formosa, has been found as an.

adulterant of this oil, which it somewhat resembles in odour. As this,

oil always contains camphor, which is absent from pure linaloe oil, the

adulterant can be detected as follows:—l

1. By preparation of the semi-carbazone. The sample is steam dis-
   tilled to remove any fixed residue, and 25 c.c. are treated with a mixture
   of 1 gram of semi-carbazide hydrochloride, 1 gram of sodium acetate and
   25 c.c. of 90 per cent, alcohol. After standing for twenty-four hours, 1
   gram of sodium bicarbonate is added, and the whole is steam distilled.
   The distillation residue is heated on a water-bath and then cooled. The
   semi-carbazone of camphor separates, if camphor be present, possibly con-
   taminated with hydrazodicarbonamide, which is removed by dissolving
   the crystals in a little alcohol, which does not dissolve this impurity. On
   dilution of the alcohol, the semi-carbazoneseparates, and on treatment with,
   dilute sulphuric acid a marked odour of camphor is perceived.


2. By oxidation of the other constituents by means of permanganate
   of potassium. Into a 2 litre flask, 300 c.c. of water and 50 grams of per-
   manganate of potassium are placed, and after standing in ice for 30
   minutes 10 grams of the oil are added drop by drop. Heat is developed,
   and the oxidation products are entirely soluble. When the reaction is-
   over (in about two hours) 200 c.c. of water are added, and the unaltered
   camphor can be steam-distilled off.
   As little as 1 per cent, of camphor in the oil can be detected by these
   methods.
   J. C. Umney has described two interesting samples of Mexican linaloe
   oil,^2 which are unquestionably natural oils, but which may be derived
   from a different species of Bursera from those which are usually distilled.
   The oils are entirely different in odour from the normal oil, and one
   would describe them as a blend of lavender and petitgrain rather than
   the normal linaloe (lily of the valley) odour.
   On examination it was found that these oils have a very high ester
   value, and by this alone are distinguished from the normal oil. The-
   following figures were obtained :—

Specific gravity

Optical rotation.

Refractive index (20°).

Esters.

Total linalol.

0-897

• 2° 30'
  1-4600
  . 52*4 per cent.
  . 54-8 ..

0-893

• 2° 30'
  1-4610
  48*7 per cent.
  57-6 „

(^1) Schimmel's Bericht, October, 1913, 69.^2 P. and E.O.R. (1916), 62.