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126. Euphorbia canariensis, Linn.—The Canary Euphorbium.

Tribe. Euphorbieae, Bartling.

Ovules solitary. Seeds albuminous. Flowers monoecious, apetalous; male and females mixed in a cup-shaped involucre.

126. Euphorbia canariensis, Linn.-The Canary Euphorbium.

Sex. Syst.. Dodecandria, Trigynia, Linn.—Monoecia, Monandria, Smith.
(Euphorbium; gummi-resina, L. D.—Concrete resinous juice, E.)

History.—The plant which yields the saline waxy-resin called in the shops gum euphorbium, is said both by Dioscorides [Lib. iii. cap. 96.] (who calls it ευφορβιον) and Pliny [Hist. Nat. lib. xxv. cap. 38, ed. Valp. Pliny calls the plant euphorbia, and the resin euphorbium (lib xxvi. cap. 34).] to have been first discovered in the time of Juba, king of Mauritania; that is, about, or a few years before, the commencement of the Christian era. Pliny says that Juba called it after his physician, Euphorbus; and that he wrote a volume concerning it, which was extant in Pliny's time. Salmasius, however, states thtt this word occurs in the writings of Meleager the poet, who lived some time before Juba. But in the passage in question the commonly received reading in the present day is not ευφορβης, but εκ φορβης [Dr. Greenhill, Dict. of Greek and Roman Biography, art. Euphorbus, vol. ii. p. 97.]

Botany. Gen. Char.Flowers collected in monoecious heads, surrounded by an involucrum consisting of 1 leaf with 5 divisions, which have externally 5 glands alternating with them. Males naked, monandrous, articulated with their pedicel, surrounding the female, which is in the centre. Females naked, solitary. Ovarium stalked. Stigmas 3, forked. Fruit hanging out of the involucrum, consisting of 3 cells, bursting at the back with elasticity, and each containing 1 suspended seed (Lindley).

Sp. Char.—Branches channelled, with 4, rarely 5, angles, armed with double, straight, spreading, dark, shining spines.

These specific characters apply to the branches, found mixed with the euphorbium of commerce. They agree with the description and figure of Tithymalus aizoides lactifluus seu Euphorbia canariensis of Plukenet. [Amalgest. Bot. vol. ii. p. 370.] This agrees with the statement of Miller, [Gardener's Dictionary, vol. i. art. Euphorbium.] who states that by looking over some euphorbium in a shop, he "found several spines amongst it, which exactly agreed with those of that plant." I feel very little hesitation, therefore, in referring the euphorbium of English commerce to E. canariensis; the species still retained by the Dublin College.

From the E. canariensis of Willdenow and of some other botanists, this plant is distinguished by its straight spines; but on examining the E. canariensis at the Kew Garden, I find as many of the spines straight as uncinate. The diameter of the stems, however, and even of the young shoots, is greater than that of stems found in the euphorbium of commerce. The species which most closely agrees with the latter in the sizes of the stems, the number of angles, and the number and directions of the spines, is Euphorbia tetragona. This species has mostly square stems; though some of the larger stems are somewhat channelled. The dried stems found in the euphorbium of commerce, however, appear to be uniformly channelled. The E. officinarum (adopted by the London College) has many angles: the Dergmuse of Jackson [Account of Morocco, 3d edit. p. 134.] has many scolloped angles. Euphorbia antiqvorum has been said to yield euphorbium, but the statement is denied by both Hamilton [trans. of the Linn. Soc. vol. xiv.] and Royle. [Bot. of the Himalayan Mountains, p. 328.]

Hab.—The Canary Islands; Africa, in the neighbourhood of Mogadore?

Extraction.—Euphorbium is thus procured: The inhabitants of the lower regions of the Atlas range make incisions in the branches of the plant, and from these a milky juice exudes, which is so acrid that it excoriates the fingers when applied to them. This exuded juice hardens by the heat of the sun, and forms a whitish-yellow solid, which drops off in the month of September, and forms the euphorbium of commerce. "The plants," says Mr. Jackson, [Op. cit.] "produce abundantly once only in four years; but this fourth year's produce is more than all Europe can consume." The people who collect it, he adds, are obliged "to tie a cloth over their mouth and nostrils to prevent the small dusty particles from annoying them, as they produce incessant sneezing." The acrid resinous juice resides in the outer or cortical portion of the stem (see ante, p. 359).

Properties.—Euphorbium consists of irregular yellowish, slightly friable tears, usually pierced with one or two holes, united at the base, and in which we find the remains of a double aculeus. These tears are almost odourless; but their dust, applied to the olfactory membrane, acts as a powerful sternutatory. Their taste is at first slight, afterwards acrid and burning.

When heated, euphorbium melts, swells up imperfectly, evolves an odour somewhat like that of benzoic acid vapour, takes fire, and burns with a pale flame. Alcohol, ether, and oil of turpentine are its best solvents; water dissolves only a small portion of it.

Composition.—Euphorbium has been the subject of several analyses—namely, in 1800, by Laudet; [Gmelin, Hand. d. Chem.] in 1809, by Braconnot; [Ann. Chim. lxviii. 44.] in 1818, by Pelletier [Bull. d. Pharm. iv. 502.] and by Mühlmann;' [Gmelin, op. cit.] in 1819, by Brandes; [Ibid.] and more recently by Drs. Büchner and Herberger. [Christison, Treatise on Poisons.]

Pelletier's Analysis.|Brande's Analysis.
Malate of lime12.2|Malate of lime18.82
Malate of potash1.8|Malate of potash4.90
Water and loss8.8|Sulphates of potash and lime, and phosphate of lime0.70
-----|Water and loss6.44
|Woody fibre5.60

Resin is the active ingredient of euphorbium. It coincides in many of its properties with ordinary resins; thus, it is reddish-brown, hard, brittle, fusible, soluble in alcohol, ether, and oil of turpentine, and somewhat less so in oil of almonds. Its leading and characteristic property is intense acridity. It differs from some resins in being slightly soluble only in alkalies. It is a compound of two resinous substances.

α. One resinous substance is soluble in cold alcohol. Its formula, according to Mr. Johnston [Phil. Trans., 1840, p. 365.], is C40H31O6.

β. The other resinous substance is insoluble in cold alcohol. The mean of Rose's analyses [Poggendorff's Annalen, xxxiii. 52.] of it gives as the composition of this resin, carbon 81.58, hydrogen 11.35, and oxygen 7.07.

Physiological Effects, α. On Animals generally.—Euphorbium acts on horses and dogs as a powerful acrid substance, irritating and inflaming parts with which it is placed in contact, and affecting the nervous system. When swallowed in large quantities, it causes gastro-enteritis (two ounces are sufficient to kill a horse); when applied to the skin, it acts as a rubefacient and epispastic. Farriers sometimes employ it, as a substitute for cantharides, for blistering horses, but cautious and well-informed veterinarians are opposed to its use.

β. On Man.—The leading effect of euphorbium on man is that of a most violent acrid, but under certain circumstances a narcotic operation has been observed. When euphorbium dust is inhaled, and also applied to the face, as in grinding this drug, it causes sneezing, redness, and swelling of the face, and great irritation about the eyes and nose. To prevent as much as possible these effects, various contrivances are adopted by different drug-grinders; some employ masks with glass eyes, others apply wet sponge to the nose and face, while some cover the face with crape. The pain and irritation, I am informed, are sometimes very great. Individuals who have been exposed for some time to the influence of this dust, suffer with headache, giddiness, and ultimately become delirious. All the workmen of whom I have inquired (and they comprise those of three large firms, including the one alluded to by Dr. Christison) agree that these are the effects of euphorbium. An old labourer assured me that this substance produced in him a feeling of intoxication; and I was informed at one drug-mill of an Irish labourer who was made temporarily insane by it, and who, during the fit, insisted on saying his prayers at the tail of the mill-horse.

Insensibility and convulsions have been produced by euphorbium. The only instance I am acquainted with is the following: A man was engaged at a mill where euphorbium was being ground, and remained in the room longer than was considered prudent. Suddenly he darted from the mill-room, and ran with great velocity down two pairs of stairs. On arriving at the ground-floor or yard he became insensible, and fell. Within five minutes I saw him: he was lying on his back, insensible and convulsed; his face was red and swollen, his pulse frequent and full, and his skin very hot. I bled him, and within half an hour he became quite sensible, but complained of great headache. He had no recollection of his flight down stairs, which seems to have been performed in a fit of delirium.

When powdered euphorbium is applied to the skin, it causes itching, pain, and inflammation, succeeded by vesication.

When swallowed, it causes vomiting and purging, and, in large doses, gastro-enteritis, with irregular hurried pulse and cold perspirations.

Uses.—Notwithstanding that it is still retained in the Pharmacopoeia, it is rarely employed in medicine. It was formerly used as an emetic and drastic purgative in dropsies, but the violence and danger of its operation have led to its disuse. Sometimes it is employed as an errhine in chronic affections of the eyes, ears, or brain; but its local action is so violent that we can only apply it when largely diluted with some mild powder, as starch or flour.

Mixed with turpentine or Burgundy pitch (or rosin), it is employed in the form of plaster, as a rubefacient, in chronic affections of the joints. As a vesicant, it is rarely employed. As a caustic, either the powder or alcoholic tincture (Tinctura Euphorbii, Cod. Hamb., prepared by digesting euphorbium ℥j, in rectified spirit lb j) is sometimes employed in carious ulcers.

Antidote.—In a case of poisoning by euphorbium, emollient and demulcent drinks, clysters (of mucilaginous, amylaceous, or oleaginous liquids), and opium, should be exhibited, and blood-letting and warm baths employed. In fact, as we have no chemical antidote, our object is to involve the poison in demulcents, to diminish the sensibility of the living part by opium, and to obviate the inflammation by blood-letting and the warm bath. If the circulation fail, ammonia and brandy will be required.

The Elements of Materia Medica and Therapeutics, Vol. II, 3th American ed., was written by Jonathan Pereira in 1853.

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