Chemistry of Essential Oils

GEEANIACE^E 489

Species Examined.

Pelargonium quercifolium minus

,, fylutinosum

Lady

Lumsden

pumilum

cucullatum.

ovale, var. Blattaria.

albescens

vitifolium.

abrotanifolium

Zonale

cri&pum,

mum

crispum,

var. maxi-

Description of Odour.

Southernwood and Tarragon

Ladanum

,, (slight odour)

,, and citral

Slight ladanum

Ladanum and weak citronellal

Citronellal and caproic ester

Diphenyl ether and butyric ester,

with trace of southernwood

Diphenyl ether

Citral and melissa

Strawberry

Citral

Weak citronellal and rose

Strong „ „

Lemon

Peppermint.

Pennyroyal

Indefinite, fruity

var. mini-
mum
„ Lady Scarborough
,, citriodorum, var., du-
mosum.
„ citriodorum, var. maxi-
mum
„ citriodorum, Prince of
Orange.
„ tomentosum
,, exstipulatum
,, tetragonum
Gharabot and Laloue
l
have published an important contribution to
that portion of the chemistry of essential oils which Dr. Charabot has
so especially made his own. To study the evolution of the various or-
ganic bodies found in the essential oils, a study which may eventually
lead to the possibility of favourably modifying the odour of oils by arti-
ficial means, it is necessary to have an accurate conception of the actual
distribution of these bodies. The paper in question deals with the distri-
bution of the organic constituents in the geranium.
In determining the free volatile acids present, they find that the
amount diminishes as one proceeds from the leaves down to the stem, the
leaves themselves containing 50 per cent, more than the stems. A care-
ful examination of the different portions of the flowering plant shows
that the terpenic compounds (by which the authors evidently mean the
geraniol compounds as well) are found to be entirely absent in the
petioles and in the stems, being found only in the leaves. It is therefore
olear that the odorous substa nces are elaborated in the leaves themselves.
This at once explains the unusual circumstance of the complete absence
of essential oil in the flower; for the oil does not at any time traverse the
stems, and therefore has no opportunity of reaching the flowers.
The essential oil obtained by separation from the distillation waters
was examined in comparison with that extracted from the water itself,
and with the whole of the oil yielded by the plant. The following results
were obtained:—

Specific gravity.

Rotation

Acidity

Saponification No.

Ester No..

Alcohols as geraniol.

Esters (geranyl tiglais)

Separated Oil. Oil

. 0-8979
. - 11° 2'
47
63-6
16-6
70-7 per cent.
7-0 „

from Water.

0-8930

• 5° 13'
  16-5
  23-2
  6-7
  77-5 per cent.
  2-8 „

Total Oil.

0'8971

• 10° 6'
  24
  57
  15
  71-8 per cent.
  6-3

(^1) Bull. Soc. Chim. Paris (1903), 838.