Chemistry of Essential Oils

66 THE CHEMISTEY OF ESSENTIAL OILS

TABLE II.—CITRONELLA OILS MIXED WITH ADULTERANT.

Characters of first 10 per cent, distilled at 20 to 40 mm. pressure.

1 2 3 4 5 6 7 8

E +

E +

E +

E +

D +

D +

D -i-

C +

5 per cent

10

15

20

5

10

20

10

Specific

Gravity

at 15-5°

resin spirit 0*855

0 848

0-841

0 8-S3

0-854

0-845

0-835

petroleum spirit 0* 848

Rotation in

100 mm.

Tube.

• 7°


• 3°


• 2°
  — 1°


• 17°


• 14°


• 8°


• 24°

Refractive

Index at

19° C.

1-4563

1-4545

1-4525

1-4505

1-4570

1-4515

1-4490

1-4514

TABLE III.—ADULTERATED CITRONELLA OILS ON THE MARKET.

Characters of first 10 per cent, distilled at 20 to 40 mm. pressure

r r\ t'\ A I. I t _ A?~ i_

1 2 3 4 5 6

Specific

Grav it y

at 15-5°

0-822

0-824

0-833

0-820

0 844

0-S36

Rotation in

100 mm.

Tube.

• 26° 48'


• 23° 50'


• 18° 20'


• 22°
  
  
  • 17° 30'
  
  
  • 29°
  
  
  
  

Refractive

Index at

19° C.

1-4492

1-4504

1-4525

1-44%

1-4540

1-4495

TABLE IV.—'BESIN AND PETROLEUM SPIRITS.

Characters of first 10 per cent, distilled at 20 to 40 mm. pressure :—

Rotation in Refractive

Index at

19° C.

1 Resin spirit

2

3 Petroleum spiritl (turpentine substi-

tute)

4 Petroleum spiritx (turpentine substi-

tute)

Specific

Gravity

at 15-5°

0-806

0-802

100 mm.

Tube.

+ 4°

+ 2° 30'

0-798

0-801

+ 1°

1-4403

1-4425

1-4435

+ 1° 30' 1-4416

The lightest fraction which the author and Bennett obtained from

the adulterated oils had a specific gravity of 0*798, an optical rotation of

• 17°, and commenced to distil at 112° C. In none of the fractions has
  any odour of paraffin been observed, nor any fluorescence—hence the
  conclusion that resin spirit is the adulterant.
  Suggested Standard.—From a consideration of these figures the fol-
  lowing standards for pure citronella oil are suggested:—

1. The oil must dissolve either clear, or at most with the slightest
   opalescence, in 10 volumes of 80 per cent, alcohol at 20J C.


2. The first 10 per cent, distilled under reduced pressure (20 to 40
   mm.) must have a specific gravity not below 0858 and a refractive index
   at 20° not below 14570.
   It may be regarded as fairly certain that no adulterated sample will
   pass these tests, although the limit for refractive index has been placed

(^1) The actual source of these turpentine substitutes has not been ascertained, as
the distillers decline to give information. They have a faint odour of paraffin, and a
distinct though slight fluorescence, and probably consist only in part of petroleum
spirit.