In his chemical examination he found the same ingredients as M. Thouvenel; but he examined them separately, and in this the merits of his labour consist.
The extractive matter reddened the tincture of Tour-nesol, but appeared of an animal nature, quickly putrefying, with a strong smell of ammonia. In distillation the black portion, not soluble in alcohol, swelled, gave out an acid fluid, a thick oil, and carbonate of ammonia, leaving a dry, shining, friable coal. The portion which alcohol dissolved, preserved, when inspissated, the smell and taste of the extract; it dissolved perfectly in water combined with potash, without separating any ammonia. In distillation it afforded similar ingredients with the insoluble portion, but in less quantity. On examination of the acid, it approached in its properties the phosphoric, though it differed from it, and seemed of a peculiar nature. It was certainly not derived from the vinegar, with which the animals are generally killed.
The green matter is not changed by the air; is insoluble in cold water, and melts in hot water, swimming on the surface like oil. Alcohol and ether dissolve it, and water separates it from these menstrua. The oxygenated muriatic acid gradually decomposes it. The substance loses its smell and colour; becomes thick and glutinous; preserving, notwithstanding repeated affusions of water, the smell of the oxygenated acid. Weak nitrous acid gives it a brown red colour, a rancid, pungent smell; adding greatly to its consistence. Caustic soda unites with it, without separating any ammonia; and the compound is disunited by acids. In a high degree of heat it forms an oily, slightly transparent fluid, which, on cooling, soon becomes solid. When urged by heat it separates into a yellow oil like that from distilled wax, and an acid water without an atom of ammonia. The parenchyma, left after the different macerations, infusions, and decoctions, when examined by caustic potash, gives a very sensible smell of ammonia. When this disappeared, the addition of muriatic acid formed a precipitate wholly of an animal nature. In the cinders, when burnt, were found carbonate of lime, calcareous phosphat, sulphat, and muriat of lime, with oxide of iron. An ounce of cantharides, in this way, afforded one drachm two grains of the black insoluble matter; as much of the yellow; about six grains more of the green matter; four drachms thirty-six grains of parenchyma; an indeterminate quantity of acid; twelve grains of calcareous phosphat; of carbonate of lime and oxide of iron two grains each, with four grains of sulphat and muriat of lime.
M. Beaupoil found from his experiments, that cantharides, given without any preparation, chiefly affected the oesophagus, the stomach, and the small intestines. Animals not killed by them suffered great pain and violent inclination to vomit; 2dly, The watery extract produced the same effects in less doses, and showed a more decided action on the urinary organs; 3dly, The black insoluble matter is less active than the extract; and, though it produced the former inconveniences, was seldom fatal; 4thly, The green matter seemed in no respect deleterious, and the yellow was scarcely more active; 5thly, The extract,the green and the yellow matter, applied to the skin, produced blisters in nearly the same time; but the yellow matter seems not to act till it is divided by wax in the form of a cerate. The author repeated these experiments on himself, and found the vesicatory properties of the cantharides resided essentially in the extractive and green part of the insect, but that the extractive exclusively acted on the urinary and genital organs.
M. Deyeux, to whom we owe this abstract in the Annals, very properly observes, that it is by no means complete. He particularly remarks it as singular, that the green matter should act as a blister, while it produces no effects on the animal economy. The author has promised to examine the subject again, and we may find some room for his further elucidations in a subsequent article.
It has been thought that they peculiarly affect the kidneys and urinary passages, proving diuretic; though whether they affect the former may be doubted, if we can believe the evidence of Dr. C. Smith and Dr. Cullen, to which our own experience may be added. Werlhof, however, gives a remarkable instance of the diuretic powers of cantharides; and tells us he had frequently experienced them in dropsy and other diseases. He gave a grain of the powder in a dose, repeating it every four hours; and it was only after the third dose, in a case of suppression of urine of many days standing, that it began to yield: still Werlhof discontinued the use of cantharides in dropsy and other diseases; and, as when the strength decays suppression spontaneously yields, we suspect that weakness rather than the remedy occasioned the flow. A blister to the loins has increased a flow of urine, but this remedy seems to act on another principle. Externally they are caustic, and are used to raise blisters, for which end Aretaeus first rubbed them on the head.
However used, they are apt to produce a strangury and inflammation of the urinary passages. When blisters are applied, the assistance of nitre, oily drinks, mucilaginous soap, and camphor, in large doses, are required. Pressing a piece of gauze into the plaster will often prevent strangury, or removing it when the blister is first raised. Washing the blistered part, when dressed, with warm milk, greatly relieves these symptoms. When imprudently taken into the stomach, they cause great heat, inflammation, bloody urine, a priapism, thirst, and a cadaverous breath. Nitre, camphor, milk, oil, mucilage of gum arabic, and copious diluting drinks, are the antidotes.
A dose of the powder may be from half a grain to six grains; and of the tincture from five to fifty drops, twice a day. By gradually increasing a small dose, a much larger quantity may be taken.
The powdered flies, the spirituous extract, or the watery one, applied to the skin, blister it equally; but the best preparation for internal use is the tincture. Mead recommends them in cutaneous complaints; and in the moist tettery eruptions of old people they have, we think, been serviceable. In incontinence of urine cantharides are useful medicines; and in blenorrhagia and leucorrhoea, they are sometimes employed, it is-said, with effect. When not used to raise blisters, they are beneficial as topical stimulants; and the tincture is occasionally employed for this purpose rubbed on para lytic limbs.
The London college directs the following preparation of the tinctura cantharidis. - Take of cantharides bruised, two drachms; of cochineal, half a drachm; of proof spirit of wine, a pint and a half; digest for eight days, and strain.
Balsams are sometimes added; and the tincture, with this addition, is thought more useful when the kidneys, womb, or bladder, are ulcerated, or the urethra is corroded; but additions are best joined extemporaneously, or interposed by themselves at proper intervals. The diuretic power of the flies is much improved by the addition of sps. aetheris nitrosi.
The unguentum Cantharuidis,formerly unguentum ad vesicatoria, is made by boiling two ounces of cantharides in eight ounces of water to four. To the strained liquor add eight ounces of the ointment of yellow resin. Evaporate this mixture in a water bath, saturated with sea salt, to the thickness of an ointment.
Its use is to dress blisters that must be kept constantly open.
Emplastrum vesicatorium. Now emplastrum can-t/iuridis. - Take of Spanish flies, one pound in powder; plaster of wax, two pounds; prepared hog's lard, half a pound: having melted the plaster and lard, a little before they coagulate, sprinkle in the flies. Most skins are softened by bathing them with warm vinegar; and if a blistering plaster is applied immediately after, in some instances it produces a speedier effect. Complaints have been often made of the failure of blisters, which have arisen from neglect or ignorance: the apothecary, therefore, should be careful to have the flies good, but not in too fine a powder; and the plaster must be neither made in too great quantity at once, nor spread with too hot a spatula.
Ceratum cantharidis, is made by mixing one drachm of Spanish flies with six drachms of cerate of spermaceti softened by heat.
In cases where the common plasters are thought to be too active, Dr. Percival commends the following composition and manner of application. It is chiefly used to keep up the discharge from blisters.
Empi.. vesicator.. Minus. - empl. vesicat. Ph. Lond. p. i. vol ij. empl. stomach, p. i. vc.1 ij. camphor in spt. vin. solut. 3 i- vel ij. m.
If a plaster of this composition be moderately warmed before the fire, then covered with a fine soft piece of gauze, it will occasion much less irriration than the usual one, produce no strangury, or but in a slight degree, and when to be removed will separate from the skin with great facility. Nor will this covering prevent its vesicating effects. Blisters may be thus applied when the skin is disposed to erysipelatous inflammation from its great sensibility, or when the eva-cuating power is wanted without the stimulus. Blisters.
Sec Lewis's Mat. Med. Percival's Essaysmed. and
Exp. tdit. 2. p. 183, 243. Memoires de la Societe Royale de Medecine, v. 1. Annales de Chimie, v.
Ca Nthi, Ca Nthus. a primitive in the Greek. As angle of the eye. Anguli oculi, also epicanthides. The cavities at the extremities of the eyelids, called the corners of the eyes; the greater can-thus is next to the nose; the lesser canthus lies towards temples.