44 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[July 20, 1872. 
M. Cloez lias investigated the essential oil, and a 
summary of liis results lias already been given. 
Tlie subject lias also been studied by Messrs. Jolm- 
son and Bossito at tlie request of Baron von Mueller. 
In France, these essences have scarcely yet gone be¬ 
yond the laboratory, but in England they have been 
used in various ways, principally in perfumery. 
Each species seems to yield its peculiar essence, but 
they only present slight differences ; they are, there¬ 
fore, classed in groups based upon similarity of 
odour, and some other characters they possess in 
common. With rare exceptions they are of a yel¬ 
lowish colour, due to an oleo-resin, a product of 
oxidation, which they hold in solution; the paler 
essences—poorer in oleo-resin—have the characte¬ 
ristic odour in the highest degree. All are obtained 
by aqueous distillation of the leaves and young 
branches. The following are the best known :— 
Essence of E. Amygdalina. — E. amygdalina is one 
of the species yielding the most essence, about 3 
litres from 100 lb. of leaves or young branches. The 
utricles containing the oil may be seen by holding 
the leaf between tlie eye and the light. The essence 
is a clear, transparent, pale yellow liquid, of piquant 
odour, resembling essence of citron, and fresh sweet 
taste, and after-taste like camphor. It boils at 
330° F. It does not evaporate so quickly -as tur¬ 
pentine. Iodine forms with it a brown solution 
which, when warmed, gives off vapours that are 
yellow, red, violet, green and blue by turns. It is 
soluble in all proportions in turpentine, volatile and 
fixed oils, benzine, naphtha, ether, chloroform, 
absolute alcohol and rectified spirit. With agitation, 
water will dissolve IT per cent, of its own weight. 
This essence does not take fire readily in contact 
with a flame unless warmed, but burns brilliantly 
and with much smoke. Like all the other essences 
it possesses great solvent powers. 
Essence of E. oleosa differs but little from the 
preceding in its physical and chemical properties; 
it is very limpid, pale yellow in colour, and sweeter 
in taste than others of its class. Its odour is simi¬ 
lar to that of mint. Boiling-point 170° C., rising 
gradually to 177° C., and then remaining stationary. 
It burns with a smokeless, scentless flame. The 
yield is about 20 oz. from 100 lb. of leaves or young 
branches. It is a good solvent of resins. 
Essence of E. sideroxylon resembles in taste and 
odour the preceding. It is very limpid, and of a 
clear straw colour. It takes fire with difficulty in 
an open vessel, but burns in a lamp with a very 
luminous flame. Yield about 10 oz. from 100 lb. of 
leaves. 
Essence of E. goniocahjx. —Pale yellow, with a 
strong, pungent, rather disagreeable odour, and 
.-strong repulsive taste. It burns with a brilliant 
-white flame without either smoke or smell. Yield 
: about 16 oz. from 100 lb. of leaves. 
Essence of E. globulus. —Very limpid, and nearly 
colourless, when prepared from young leases; the 
utricles containing the essence being in them larger, 
but less numerous than in the developed leaf, and 
the yield less in quantity. 
Essence of E. corymbosa. —Colourless, with an 
odour sweetish when compared to the others, and 
recalling the essence of E. amygdalina, combined 
with a trace of oil of roses, but with neither its 
pungency nor freshness. The taste is slightly bitter, 
* Volume I. (1870-71) p. 78. 
leaving an after flavour of mint irritating to the 
throat. 
Essence of E. fabrorum. —Limpid, transparent, 
reddisli-brown, With a sweetish odour, not quite so 
disagreeable as E. goniocahjx. 100 lb. of fresh 
leaves yield about 8 oz. of essential oil. 
Essence of E.fissilis. —Resembling the preceding; 
and the yield being the same. Odour less strong 
and comparatively agreeable. Good solvent for 
resins. 
Essence of E. odorata. —Yield variable but in¬ 
considerable ; colour pale greenish-yellow; odour 
resembling camphor. 
Essence of E. T Yoollsii. —Odour of camphor ; 
taste sweet and aromatic; yield 3 oz. from 100 lb. 
of leaves. 
Essence of E. rostrata. —Not very abundant, 
100 lb. of leaves } T ielding scarcely 1 oz. It varies in 
colour from pale yellow to a reddish amber tint. 
Odour and taste similar to that of E. odorata. 
Essence of E. viminalis. —Colour yellowish green ; 
odour disagreeable ; taste similar to that of E. odo¬ 
rata. Yield inconsiderable. 
These essences are employed in the manufac¬ 
ture of varnish. Some resins do not dissolve 
in them at ordinary temperatures ; but all or nearly 
all, dissolve upon the application of heat. Gutta 
percha, which resists for a long time their solvent 
action in the cold, dissolves when the temperature 
is raised, but a portion is deposited upon the cooling 
of the liquid. 
The Eucalyptus yields as many gum resins as 
there are species, but they are all very similar in 
then- physical characters. They are found in trees 
of all ages, in cavities running in the direction of 
the grain of the wood. They might be obtained in 
a liquid state by means of incisions, but this method 
has not hitherto been practised. When solid they 
form little angular masses, occasionally striated and 
enclosing pieces of the wood ; the colour is usually 
a deep red-brown, sometimes veined with yellow or 
olive green and dull in appearance; sometimes of a 
beautiful uniform red shade, transparent and bril¬ 
liant. Dried in a water bath they lose 20 per cent, 
of their weight; present a vitreous fracture and are 
easily powdered. They have a styptic taste, with¬ 
out bitterness, colour the saliva red, and adhere to 
the teeth. All are not equally soluble in water; 
the gum of E. fabrorum being completely soluble, 
even in the cold, while that of E. corymbosa 
is insoluble without the addition of a few drops of 
ammonia. In aqueous solution all the gums give 
an acid reaction with litmus paper, but with other 
reagents they offer points of difference. The pre¬ 
cipitate obtained with solution of gelatine does not 
appear to correspond in quantity with the strong 
astringent taste ; sometimes no precipitate is formed 
at all. With acetate of lead an abundant gelati¬ 
nous precipitate is formed; salts of iron give rise to 
various shades of green or black. The mineral 
acids cause a thick flocculent deposit. Some of these 
gums, especially that from E. resinifera, are imported 
into this country under the name of “ Botany Bay 
Kino.”* 
Finally, there are two varieties of a peculiar 
substance commonly called “ Eucalyptus manna.” 
One occurs in small, rounded, irregular opaque white 
It is 
punc- 
masses, having an agreeable sweet taste, 
exuded abundantly in summer throu 
gh 
* See Phakm. Jouen. Third Series, Yol. II. p. 102. 
