Chemistry of Essential Oils

LEGUMINOS^E 477

Sample (1) was a consignment via New York,

direct import of undoubted purity.

Essential Oil of Carthagena Copaiba—

Sample (2) was a

Sp. Gr.

0-894

0-8972

0-899

0-901

aD.

• 19° 30'
  
  
  • 19° 30'
  
  
  
  


• 22° 30'


• 7° 30'

Yield p. Cent.

40

50

40

45

Sp. Gr.

0-903

0*904

0-905

0-905

ao.

• 6°


• 2°


• 7°


• 10'

0'

30'

30'

30'

Yield p. Cent,

52

45

45

50

The abnormally low optical rotation of several of these oils indicates

probably some change in the botanical source, with possibly a wider

collection than in former years, no adulteration being detected. Some

samples contained from 1*2 to 10 per cent, of admixed water.

Essential Oil of Maracaibo Copaiba—

Specific gravity 0-900 ; aD - 6°; yield, 48 per cent.

Essential Oil of Maranham Copaiba—

Sp. Gr.

0-896

0-899

0-899

0-8995

0-900

0-900

ential Oil

Sp. Gr.

0-886

0-891

0-891

0-891

0*8912

0-8915

OD

- 18°

- 18°

- 19°

- 15°

- 13°

- 14°

30'

30'

0'

30'

30'

0'

of Para

Sp.

• 29°
  
  
  • 25°
  
  
  
  


• 24°


• 23°


• 24
  °
  
  
  • 24°
  
  
  
  

0'

12'

0'

0'

14'

30'

Yield p. Cent.

36

45

43

45

48

52

Copaib—

Yield p. Cent.

52

5

50

45

50

50

Sp. Gr.

0-900

0-9005

0-901

0*901

0-9016

0-902

Sp. Gr.

0-8916

0-8965

0-897

0-97

0-906

0-908

D. Yield p. Cent

• 14C' 30'


• 16°


• 16°


• 13° 20'


• 12° 18'


• 13° 30'

40

40

45

56

50

50

AD. Yield p. Cent.

• 27° 30'


• 17° 30'


• 21° 20'


• 18° 44'


• 30° 0'


• 29° 0'

50

60

70

64

64

72

Cocking

• considers that the first 10 per cent, distilled in vacuo of a
  copaiba oil should have a higher laevo-rotation than that of the oil itself,
  and that a lower value indicates the presence of an adulterant. Although
  the author dissents from Cooking's conclusions, the fact that the British
  Pharmacopoeia has based an official test on it causes it to be of consider-
  able importance.
  Cooking's conclusions are as follows:—
  2
  To detect adulteration of copaiba with the African oleo-resin, the
  sample is submitted to distillation either by steam, or in vacuo, and the
  volatile oil so obtained is dried, then fractionally distilled to dryness in
  vacuo. Ten equal fractions are collected, and the aD of each of these
  determined in a 100 mm. tube.
  If the sample be pure the figures obtained will all be negative, and
  they will increase arithmetically from the first to the last fraction (that
  is, each successive fraction is more strongly laevo-rotatory than the pre-
  ceding one), although not regularly. If, now, the rotation of the first
  fraction be subtracted from that of the tenth, a figure will be obtained
  which varies very little for genuine samples, and is always a negative
  quantity. This figure, the " difference value," will only vary - 3*7° to

• 7-6°.
  1
  Chemist and Druggist, 77 (1910), 119.
  3
  Year Book of Pharmacy (1911), 128.