_Euphorbium_, _Gum Euphorbium_; F. _Gomme-résine d’Euphorbe_; G.
_Euphorbium_.
=Botanical Origin=—_Euphorbia resinifera_ Berg, a leafless, glaucous,
perennial plant resembling a cactus, and attaining 6 or more feet in
height. Its stems are ascending, fleshy and quadrangular, each side
measuring about an inch. The angles of the stem are furnished at
intervals with pairs of divergent, horizontal, straight spines about ¼
of an inch long, and confluent at the base into ovate, subtriangular
discs. These spines represent stipules: above each pair of them is a
depression, indicating a leaf-bud. The inflorescence is arranged at the
summits of the branches, on stalks each bearing three flowers, the two
outer of which are supported on pedicels. The fruit is tricoccous, ³/₁₀
of an inch wide, with each carpel slightly compressed and keeled.[2070]
The plant is a native of Morocco, growing on the lower slopes of
the Atlas in the southern province of Suse. Dr. Hooker and his
fellow-travellers met with it in 1870 at Netifa and Imsfuia,[2071]
south-east of the city of Morocco, which appears to be its westward
limit.
=History=—Euphorbium was known to the ancients. Dioscorides[2072] and
Pliny[2073] both describe its collection on Mount Atlas in Africa, and
notice its extreme acridity. According to the latter writer, the drug
received its name in honour of Euphorbus, physician to Juba II., king
of Mauritania. This monarch, who after a long reign died about A.D. 18,
was distinguished for his literary attainments, and was the author of
several books[2074] which included treatises on opium and euphorbium.
The latter work was apparently extant in the time of Pliny.
[2070] Fig. in Bentley and Trimen’s _Med. Plants_, part 24 (1877).
[2071] Or Mesfioua, according to Ball, who also quotes the province
Demenet.—_Journ. of the Linnean Soc._ Bot. xvi. (1878) 662.
[2072] Lib. iii. c. 86.
[2073] Lib. v. c. 1; lib. xxv. c. 38.
[2074] Smith, _Dict. of Greek and Roman Biography_, ii. (1846) 636.
Euphorbium is mentioned by numerous other early writers on medicine, as
Rufus Ephesius, who probably flourished during the reign of Trajan, by
Galen in the 2nd century, and by Vindicianus and Oribasius in the 4th.
Aëtius and Paulus Ægineta, who lived respectively in the 6th and 7th
centuries, were likewise acquainted with it; and it was also known to
the Arabian school of medicine. In describing the route from Aghmat to
Fez, El-Bekri[2075] of Granada, in 1068, mentioned the numerous plants
“El-forbioun” growing in the country of the Beni Ouareth, a tribe of
the Sanhadja; the author noticed the spiny herbaceous stems of the
shrub abounding in the purgative milky juice.
Höst[2076] (1760-1768) stated that the plant, which he also correctly
compared with Opuntia, is growing near Agader, south of Mogador.
The plant yielding euphorbium was further described at the beginning
of the present century by an English merchant named Jackson, who had
resided many years in Morocco. From the figures he published,[2077]
the species was doubtfully identified with _Euphorbia canariensis_
L., a large cactus-like shrub, with quadrangular or hexagonal stems,
abounding on scorched and arid rocks in the Canary Islands.
In the year 1749 it was pointed out in the (_Admiralty_) _Manual of
Scientific Enquiry_, that the stems of which fragrants are found in
commercial euphorbium, do not agree with those of _E. canariensis_.
Berg carried the comparison further, and finally from the fragments
in question drew up a botanical description, which with an excellent
figure he published[2078] as _Euphorbia resinifera_. The correctness
of his observations has been fully justified by specimens[2079] which
were transmitted to the Royal Gardens, Kew, in 1870, and now form
flourishing plants.
[2075] _Description de l’Afrique septentrionale_, traduite par M. de
Slane, _Journal asiatique_, xiii. (Paris, 1859) 413.
[2076] _Nachrichten von Marokos und Fes_, Kopenhagen, 1781. 308.
[2077] _Account of the Empire of Morocco and the district of Suse_,
Lond. 1809. 81. pl. 7.—The plate represents an entire plant, and also
what purports to be a portion of a branch of the natural size. The
latter is really the figure of a different species,—apparently that
which has been recently named by Cosson _Euphorbia Beaumierana_.
[2078] Berg und Schmidt, _Offizinelle Gewächse_, iv. (1863) xxxiv. d.
[2079] They were procured by Mr. William Grace, and forwarded to
England by Mr. C. F. Carstensen, British Vice-Consul at Mogador.
The drug has a place in all the early printed pharmacopœias.
=Collection=—Euphorbium is obtained by making incisions in the green
fleshy branches of the plant. These incisions occasion an abundant
exudation of milky juice which hardens by exposure to the air,
encrusting the stems down which it flows; it is finally collected
in the latter part of the summer. So great is the acridity of the
exudation, that the collector is obliged to tie a cloth over his mouth
and nostrils, to prevent the entrance of the irritating dust. The drug
is said to be collected in districts lying east and south-east of the
city of Morocco.
=Description=—The drug consists of irregular pieces, seldom more
than an inch across and mostly smaller, of a dull yellow or brown
waxy-looking substance, among which portions of the angular spiny
stem of the plant may be met with. Many of the pieces encrust a tuft
of spines or a flower-stalk or are hollow. The substance is brittle
and translucent; splinters examined under the microscope exhibit
no particular structure, even by the aid of polarized light; nor
are starch granules visible.[2080] The odour is slightly aromatic,
especially if heat is applied; but 10 lb. of the drug which we
subjected to distillation afforded no essential oil. Euphorbium has
a persistent and extremely acrid taste; its dust excites violent
sneezing, and if inhaled, as when the drug is powdered, occasions
alarming symptoms.
=Chemical Composition=—Analysis of euphorbium performed by one of
us[2081] showed the composition of the drug to be as follows:—
Amorphous resin, C₁₀H₁₆O₂ 38
Euphorbon, C₁₃H₂₂O 22
Mucilage 18
Malates, chiefly of calcium and sodium 12
Mineral compounds 10
------
100
The amorphous resin is readily soluble in cold spirit of wine
containing about 70 per cent. of alcohol. The solution has no acid
reaction, but an extremely burning acrid taste: in fact it is to the
amorphous indifferent resin that euphorbium owes its intense acridity.
By evaporating the resin with alcoholic potash and neutralizing the
residue with a dilute aqueous acid, a brown amorphous substance, the
_Euphorbic Acid_ of Buchheim,[2082] is precipitated. It is devoid of
the acridity of the resin from which it originated, but has a bitterish
taste.
From the drug deprived of the amorphous resin as above stated, ether
(ether or petroleum) takes up the _Euphorbon_, which may be obtained
in colourless, although not very distinct crystals, which are at
first not free from acrid taste. But by repeated crystallizations
and finally boiling in a weak solution of permanganate of potassium,
they may be so far purified as to be entirely tasteless. Euphorbon is
insoluble in water; it requires about 60 parts of alcohol, sp. gr.
0·830, for solution at the ordinary temperature. In boiling alcohol
euphorbon dissolves abundantly, also in ether, benzol, amylic alcohol,
chloroform, acetone, or glacial acetic acid.
Euphorbon melts at 116° C. (113° to 114°, Hesse) without emitting
any odour. By dry distillation a brownish oily liquid is obtained,
which claims further examination. If euphorbon dissolved in alcohol
is allowed to form a thin film in a porcelain capsule, and is then
moistened with a little concentrated sulphuric acid, a fine violet hue
is produced in contact with strong nitric acid slowly added by means
of a glass rod. The same reaction is displayed by _Lactucerin_ (see
Lactucarium), to which in its general characters euphorbon is closely
allied.
[2080] By careful investigation a very few are found at last.
[2081] Flückiger in Wittstein’s _Vierteljahresschrift für prakt.
Pharmacie_, xvii. (1868) 82-102.—The drug analysed consisted of
selected fragrants, free from extraneous substances.
[2082] Wiggers and Husemann, _Jahresbericht_, 1873. 559.
Hesse (1878) assigns to euphorbon the formula C₁₅H₂₄O, and points out
that its solutions in chloroform or ether are dextrogyrate.
As to the mucilage of euphorbium, it may be obtained from that portion
of the drug which has been exhausted by cold alcohol and by ether.
Neutral acetate of lead, as well as silicate or borate of sodium,
precipitate this mucilage, which therefore does not agree with gum
arabic.
If an aqueous extract of euphorbium is mixed with spirit of wine,
and the liquid evaporated, the residual matter assumes a somewhat
crystalline appearance, and exhibits the reactions of _Malic Acid_.
Subjected to dry distillation, white scales and acicular crystals of
_Maleic_ and _Fumaric Acids_, produced by the decomposition of the
malic acid, are sublimed into the neck of the retort. A sublimate of
the same kind may sometimes be obtained directly by heating fragments
of euphorbium. Among the mineral constituents of the drug, chloride of
sodium and calcium are noticeable; scarcely any salt of potassium is
present.
=Commerce=—The drug is shipped from Mogador. The quantity imported into
the United Kingdom in 1870 is given in the _Annual Statement of Trade_
as 12 cwt.
_Uses_—Euphorbium was formerly employed as an emetic and purgative,
but as an internal remedy it is completely obsolete. We have been told
that it is now in some demand as an ingredient of a paint for the
preservation of ships’ bottoms.