Qualities. The leaves, when properly dried, have a slight narcotic odour, and a bitter nauseous taste, and when reduced to powder, a beautiful green colour. Chemical Composition. Extractive matter, and a green resin, in both of which the narcotic properties reside; they appear also to contain ammonia, and some other salts.^[492] Solubility. Both water and alcohol extract their virtues, but decoction injures them. Incompatible Substances. See Infusum Digitalis. Medicinal Uses. It is directly sedative, although some maintain the contrary opinion, diminishing the frequency of the pulse, and the general irritability of the system, and increasing the action of the absorbents, and the discharge by urine. The effects appear to be in a great degree connected with its sensible influence upon the body, which is indicated by feelings of slight nausea and languor; accordingly, every attempt to prevent these unpleasant effects, or to correct the operation of digitalis, by combining it with aromatic, or stimulant medicines, seems to be fatal to the diuretic powers of the remedy. Dr. Blackall, in his “Observations upon the cure of Dropsies,” has offered some remarks which bear upon this point, and to which I have before referred. See page 96 & 150.

Several of the formulæ introduced under the class of diuretics are combinations supported by high authority, but it is doubtful whether their adoption can be sanctioned upon principle; they are however well calculated to illustrate the nature of diuretic compounds, and this is the only purpose for which they were selected. See Form: 103. The French have introduced in their new Codex, an ethereal tincture, Tinctura Ætherea Digitalis purpureæ, in which the sedative influence of the plant must be entirely overwhelmed by the stimulant properties of the menstruum. Under the head of Diuretics, I have so fully considered the value of diuretic combinations, and the modus operandi of Digitalis, that it is unnecessary to dwell upon the subject in this place. Digitalis has considerable influence over the action of the heart; and in certain diseases, attended with inordinate motions of that organ, it proves eminently serviceable; I have employed it with great satisfaction in cases of palpitation connected with a state of general irritability, so frequently occurring in female disorders; and according to my observations where it succeeds, opium generally does harm. Form: 32. Forms of Exhibition. In substance, tincture, or infusion; the latter form is most efficient as a diuretic. Dose of the powdered leaves gr. j, in a pill, twice a day; the augmentation of the dose should proceed at the rate of one-fourth of the original quantity, every second day, until its operation becomes apparent, either on the kidneys, or on the constitution generally. If it produce such a disturbance in the primæ viæ as to occasion vomiting or purging, its diuretic powers will be lost; in such a case the addition of a small portion of opium, or opiate confection, may be expedient. The distressing effects of an overdose are best counteracted by tincture of opium in brandy and water, and by the application of a blister to the pit of the stomach. A London Surgeon has lately stated that he has prescribed the tincture of Digitalis, in the dose of twenty-five drops, three times a day, in barley-water, with great success in Gonorrhæa. Officinal Preparations. Infus: Digitalis. L.E. Tinct: Digital: L.E.D. Decoct: Digitalis: D. It is very important that the leaves of this plant be properly collected, and accurately preserved; they should be gathered when the plant is beginning to flower, and, as it is biennial, in the second year of its growth; the largest and deepest coloured flowers should be also selected, for they are the most powerful; they should be also carefully dried until they become crisp, or they will lose much of their virtue; the too common method of tying them in bundles, and hanging them up to dry, should be avoided, for a fermentation is produced by such means, and the parts least exposed soon become rotten. The powdered leaves ought to be preserved in opaque bottles, and kept from the action of light as well as of air and moisture; a damp atmosphere has, upon a principle already explained, a very injurious operation, by carrying off those faint poisonous effluvia with which its efficacy seems to be ultimately connected.

The virtues of this plant are extracted by boiling water, but long coction destroys them; the usual and best form in which it can be administered is that of decoction or infusion. This plant is much more appreciated on the continent than in this country; we rarely use it except in cutaneous affections; Professor Richter of Gottingen states that he has employed it in Phthisis Pituitosa with very extraordinary success; and Sir A. Crichton says that in the few cases of chronic tubercular Phthisis in which he has given it, it appeared to increase the powers of the Sarsaparilla with which it was usually combined. Officinal Prep: Decoct: Dulcam: L.

This plant appears from the testimony of Dioscorides and other writers, to have been employed by the ancient physicians with much confidence and success. All the parts of the plants were considered as purgative, although not in an equal degree; thus Geoffroy, “radicum vis cathartica major est quam foliorum, minor vero quam fructuum.” This question has very lately been set at rest by the judicious experiments of Dr. Clutterbuck,^[493] which prove that the active principle of this plant resides more particularly in the juice which is lodged in the centre of the fruit, and which spontaneously subsides from it; when this substance is freed from extraneous matter, it possesses very energetic powers, and appears to me to be entitled to consideration as a distinct proximate principle, which I shall venture to call Elatin. See Extractum Elaterii.

This substance is what is generally termed a gum-resin; that is, a compound consisting of gum, resin, and volatile oil: late researches however seem to shew that these bodies are compounds of a peculiar character, consisting of a volatile substance, something between essential oil and a constituent which possesses the properties of extractive rather than those of gum.

True Elemi has a fragrant aromatic odour, not unlike that of fennel-seeds, but more potent. Sp. gr. 1·0182. When powdered it mixes with any unguent; it also combines with balsams and oils, and by the aid of heat, with turpentine. Uses. It is only employed for forming the mild digestive ointment which bears its name, viz. Unguent: Elemi comp: L.D.

The principles upon which this form of preparation is to be constructed are fully detailed at p. 207.

Emplastrum Ammoniaci. L. Ammoniacum reduced to a suitable consistence by distilled vinegar. It adheres to the skin without irritating it, and without being attended with any unpleasant smell.^[494] There is a peculiar disease of the knee, to which servant maids, who scour floors upon their knees, are liable, and for which this plaster is a specific. I have also found it particularly eligible in cases of delicate women with irritable skins.

Emplastrum Ammoniaci cum Hydrargyro. L.D. The mercury in this plaster is in the state of oxidation ad minimum. It is discutient and resolvent, and is applicable to indurated glands, and venereal nodes, and for removing indurations of the periosteum, remaining after a course of mercury; the addition of the ammoniacum increases the stimulating and discutient powers of the mercury, which gives this plaster a superiority over the Emplastrum Hydrargyri. It is also powerfully adhesive.

Emplastrum Assafœtidæ. E. Emplast. Plumbi and Assafœtida, of each two parts, galbanum and yellow wax, of each one part. I have seen it useful in flatulent cholic, when applied over the umbilical region.

Emplastrum Cantharidis. L. Emplast: Cantharidis vesicatoriæ. E.D. A variety of substances has in different times been employed for producing vesication, but no one has been found to answer with so much certainty and mildness as the Lyttæ. All the others are apt to leave ill conditioned ulcers: true it is, that the emplastrum lyttæ will occasionally fail, but this is generally attributable to some inattention, or want of caution on the part of the person who prepares it; in spreading it, the spatula should never be heated beyond the degree of boiling water; the plaster also should be sufficiently secured on the part by slips of adhesive plaster, but it ought not to be bound on too tight; where the cuticle is thick, the application of a poultice for an hour, previous to that of the blister, will be useful, or the part may be washed with vinegar. In consequence of the absorption of the active principle of the Lyttæ, blisters are apt to occasion strangury and bloody urine; it has been a problem therefore of some importance to discover a plan by which such an absorption may be obviated, for this purpose, camphor has been recommended to be mixed with the blistering composition, and a piece of thin gauze has been interposed between the plaster and the skin; but it has been lately found, that ebullition in water deprives the Cantharides of all power of thus acting on the kidneys, without in the least diminishing their vesicatory properties: the ordinary time required for the full action of a blister is ten or twelve hours, but if it be applied to the head, double that period will be necessary. Children, owing to delicacy of skin, are more speedily blistered, the epispastic may therefore be removed earlier. In some cases the blistered parts, instead of healing kindly, become a spreading sore; whenever this occurs, poultices are the best applications; it may arise from a peculiar irritability of the constitution, although I apprehend that it not unfrequently depends upon the sophistication of the plaster with euphorbium. In cases where it is desirable to keep up the local irritation, it is still a question with some practitioners whether it be more advisable to encourage a discharge from the vesicated part by some appropriate stimulant, or to renew the vesication at short intervals by repeated blisters; the latter mode is perhaps to be preferred, as being more effectual, and certainly less troublesome to the patient: it has moreover been stated,^[495] that by a repeated application of this nature, the influence excited appears to extend much deeper, so as to derive a greater quantity of blood from the immediate neighbourhood of the vessels, or from the vessels themselves which are in a state of disease, than the influence excited by an application less stimulating upon the surface of a part already abraded. The character of the discharge would likewise appear essentially different; it being in the latter cast a purulent secretion from the superficial exhalants of the surface only; in the former, a copious effusion of serum, mixed with a large portion of lymph, produced from a deeper order of vessels.

Emplastrum Ceræ. L. Emplast: Simplex. E. This is the Emplast: Ceræ of P.L. 1787, the Emplast: Attrahens of 1745, so called because it was formerly employed to keep up a discharge from a blistered surface, and the Emplastrum de melilolo simplex of 1720.

Emplastrum Cumini. L. A valuable combination of warm and stimulant ingredients.

Emplastrum Galbani Compositum. L.D. Emplast: Gummos. E. More powerful than the preceding plaster. In indolent glandular enlargements of a strumous character, in fixed and long continued pains in the neighbourhood of the joints, or in anomalous or arthritic pains of the ligaments, this plaster is said to be frequently beneficial.

Emplastrum Hydrargyri. L.E. The mercury in this plaster is in the state of oxidation ad minimum; each drachm containing about fifteen grains of mercury, (sixteen grains, Edinb.) It is alterative, discutient, and sometimes sialogogue; but it is inferior to the Emplast: Ammoniac: cum Hydrargyro.

Emplastrum Opii. L.E. This plaster is supposed to be anodyne, but it is very doubtful whether the opium can, in such a state, produce any specific effect. See Form: 5.

Emplastrum Picis Compositum. L. Emplast: Picis burgundicæ, P.L. 1787. It is stimulant and rubefacient, and is often employed as an application to the chest, in pulmonary complaints; the serous exudation however which it produces, frequently occasions so much irritation that we are compelled to remove it.

Emplastrum Plumbi. L. Emplast: Oxydi Plumbi semi-vitrei. E. Emplast: Lythargyri. P.L. 1787. Emplast: commune, 1745. Diachylon^[496] Simplex, P.L. 1720. This is a very important plaster, since it forms the basis of a great many others; under the name of Diachylon it has long been known, and employed as a common application to excoriations, and for retaining the edges of fresh cut wounds in a state of apposition, and at the same time for defending them from the action of the air; when long kept it changes its colour, and loses its adhesive properties, and by high temperature the oxyd of lead is revived.^[497]

Emplastrum Resinæ. L. Olim, Emplast: commune adhæsivum, P.L. 1745. Emplast: Resinosum. E. Emplast: Lithargyri cum Resina. D. It is defensive, adhesive, and stimulant.^[498]

Emplastrum Saponis. L.D. Emplastrum Saponaceum. E. The Soap Plaster is said to be a mild discutient application.

[The boneset is a plant indigenous to the United States, and is to be found in the neighbourhood of marshes and low situations. It is intensely bitter and somewhat astringent. According to the analysis of Dr. Andrew Anderson of New-York, it yields, 1. A free acid; 2. Tannin; 3. Extractive matter; 4. A gummy matter; 5. A resin; 6. Azote; 7. Lime, probably the acetate of lime; 8. Gallic acid, probably modified; 9. A resiniform matter, soluble in water and in alcohol, and which seems to contain a bitter principle. It also appears from this analysis that the free acid may be obtained from all parts of the plant—that tannin is obtained in much the largest quantity from the leaves, and least from the roots—that the extractive and gummy matter reside chiefly in the roots—that the leaves and flowers also contain a larger proportion of resin than the roots—and that azote exists in the flowers, leaves, and roots. The principal properties of the boneset are those of a tonic and diaphoretic. The diseases in which it has been prescribed with success are intermitting and remitting fevers, typhoid peripneumony and catarrh. It may be given in powder, infusion, or tincture. When given as a tonic, the tincture is the preferable form. The dose of the powder is from 20 to 30 grains. When used as a sudorific, it is to be taken in infusion, and in large quantities.]

[This plant is peculiar to the United States. The root is perennial, and of a sweetish taste. By analysis it yields caoutchouc, resin, mucus, and fecula. In its medicinal properties it resembles, and perhaps equals, the common ipecacuanha. As an emetic the dose is from 15 to 25 grains.]

Qualities. This substance is imported from Barbary, in drops or irregular tears; its fracture is vitreous; it is inodorous, but yields a very acrid burning impression to the tongue. Chemical Composition. It is what is termed a gum resin, but its acrid constituent is exclusively in that portion which is soluble in alcohol, and which might be named Euphorbin; it appears to form as much as 37 per cent. to which are added of wax 19, malate of lime 20·5, malate of potass 2, and water 5. Solubility. Water by trituration is rendered milky, but dissolves only one-seventh part; and alcohol one-fourth of it. Uses. Internally administered, it proves very violently drastic, but it is never employed except as an errhine, cautiously diluted with starch, or some inert powder. The Indian practitioners administer it as a purge in obstinate visceral obstructions; and in those cases of costiveness which so often attend an enlargement and induration of the spleen and liver. Farriers use it for blistering horses, and there is good reason to believe that it is sometimes fraudulently introduced to quicken the powers of our Emplastrum Cantharidis. It enters as an ingredient into a plaster, which has been much celebrated by Cheselden and others, as a stimulating application, to relieve diseases of the hip-joint, and to keep up inflammation of the skin in chronic states of visceral inflammation; the following is its composition. ℞. Emplast: Picis comp: ℥iv.—Euphorbiæ gum-resinœ ʒss.—Terebinth: Vulgar, q. s. Caution, in pulverizing this substance, the dispenser should previously moisten it with vinegar to prevent its rising and excoriating his face.

These preparations are obtained by evaporating the watery or spirituous solutions of vegetables, and the native juices obtained from fresh plants by expression, to masses of a tenacious consistence. The London college does not arrange the extracts under the titles of watery and resinous, which is the arrangement of the Edinburgh Pharmacopœia, nor under those of simple and resinous, which is the division observed in that of Dublin, but rejecting all specific distinctions, includes, under the generic appellation of extract, both the species, as well as all the inspissated juices. Since however the former of these arrangements will afford greater facilities for introducing the observations which it is my intention to offer, it is retained in this work.

The chemical nature of extracts must obviously be very complicated and variable, depending in a great degree upon the powers of the menstruum employed for their preparation; although Fourcroy and Vauquelin considered that one peculiar principle was the basis of them all, which they called Extract, Extractive, or the Extractive Principle. It is distinguished by the following characters, viz.

It has a strong taste, varying in different plants; it is soluble in water, and in alcohol when it contains water, but is quite insoluble in absolute alcohol and æther; its aqueous solution soon runs into a state of putrefaction; by repeated solutions and evaporations, or by long ebullition, it acquires a deeper colour, and in consequence of its combination with oxygen it becomes insoluble and inert, a fact which is of extreme importance as it regards its pharmaceutical relations; it unites with alumine, and if boiled with its salts, precipitates it, hence wool, cotton, or thread, impregnated with alum, may be dyed of a fawn-colour by extractive; its habitudes with alkalies are very striking, combining most readily and forming with them compounds of a brownish yellow colour, which are very soluble in water; if to a colourless and extremely dilute solution of extractive, an alkali be added, a brown or yellowish tint is immediately produced, so that under certain circumstances I have found an alkali to be a serviceable test in detecting the presence of extractive matter. The usual brown hue of the liquor ammoniæ acetatis, is owing to the action of the ammonia upon traces of vegetable extractive contained in the distilled vinegar.

Much confusion has arisen from the word extract having been employed in this double meaning,—chemically to express a peculiar vegetable proximate principle, and pharmaceutically to denote any substance however complicated in its nature, which has been obtained by the evaporation of a vegetable solution or a native vegetable juice. It is in the latter sense that it is to be understood in the present article.

The different proximate principles of vegetable matter undergo various and indefinite changes with such rapidity, when acted upon by heat, that the process of extraction must necessarily more or less impair the medicinal efficacy of a plant, and not unfrequently destroy it altogether, and hence, says Dr. Murray, “with the exception of some of the pure bitters, as gentian, or some of the saccharine vegetables, as liquorice, there is no medicine perhaps but what may be given with more advantage under some other form;” this however is not exactly true, for when care is taken in the preparation, we are thus enabled to concentrate many very powerful qualities in a small space, and the process lately adopted of evaporating the solutions by the aid of steam, contributes very materially to obviate the failures which so frequently occurred from a too exalted temperature. There is, for instance, great reason to suppose that the black colour which so often characterises the extracts of commerce, is frequently owing to the decomposition and carbonization of the vegetable matter; the colour therefore of an extract becomes in some degree a test of its goodness. I have lately examined the extracts of commerce with some attention, and I find the presence of iron by no means an uncommon circumstance; when thus contaminated they afford a very dirty coloured solution, which rapidly becomes darker on exposure to air. The extracts mentioned in the preface as made by Mr. Barry, by evaporating in vacuo, deserve the attention of the profession; the principle is without doubt well calculated to secure the active matter of the plant from those changes to which it is constantly liable during the ordinary operation of inspissation. The extracts, thus prepared, are certainly more powerful in their effects, and some few of them appear also to possess properties which are not to be distinguished in the Extracts of Commerce; those of narcotic plants, as Hemlock, Hyoscyamus, &c. are decidedly more efficacious; where the practitioner directs their use, he should, to prevent any mistake, add the words in vacuo præp. as in Formula 4; for on account of the difference in the strength of these preparations, and of those prepared by the ordinary method, they cannot be indiscriminately employed. Dr. John Davy, at my request, has made trial of these extracts in the Military Hospital at Fort Pitt, and as his results coincide with those obtained in my own practice, I shall relate, under the history of each Extract, the comparative conclusions which have been obtained.

These extracts must, of course, contain all the principles of a plant which are soluble in water, such as gum, extractive matter, tannin, cinchonin, sugar, fecula, &c. together with any soluble salts which the vegetable may contain. I have also found by experiment that an aqueous extract may even contain, in small proportions, certain elements which, although quite insoluble in water, are nevertheless partially soluble in vegetable infusion. This law of vegetable chemistry has never been expressed, although we have repeated instances of its truth, and a knowledge of it may explain some hitherto unintelligible anomalies. It has been stated that extractive matter is perfectly insoluble in æther, but Mr. A. Thomson found repeatedly, that if a small portion of resin was present, æther would in that case take up extractive in combination with the resin which it so readily dissolves. As decoction or infusion is a process preliminary to that of extraction, the practitioner must refer to those articles for an enumeration of the different sources of error which are attached to them.

Extractum Aloes Purificatum. L. The resinous element of the aloes is got rid of in this preparation; on which account it is supposed, in an equal dose, to be more purgative and less irritating. Dose, gr. x to xv. Form: 12, 13, 36.

Extractum Anthemidis. L.E. Extract. Florum Chamœmeli. D. This extract furnishes an example of the change effected on some plants by the process of extraction; in this case the volatile oil is dissipated, and a simple bitter remains, possessing scarcely any of the characteristic properties of chamomile. This remark, however, does not apply to this extract, when prepared in vacuo. I have lately received from Mr. Pope of Oxford Street, a specimen which retains, in the most eminent degree, all the odour and taste of the recent flower. Dose, gr. x–℈j.

Extractum Cinchonæ. L.D. The properties of the bark in this preparation are much invalidated, owing to the oxidizement of its extractive matter, which takes place to such an extent, that not more than one half of the preparation is soluble in water; it is not however altogether devoid of utility, and will often sit lightly on the stomach, when the powder is rejected. Its taste is very bitter, but less austere than the powder. The most beautiful extract of bark, which I have ever seen, was prepared by Mr. Barry of Plough Court; its colour was that of a deep brilliant ruby, and its flavour preserved all the characteristic peculiarity of the recent substance.^[499] Dose, grs. x to ʒss. Fourteen ounces of the bark will yield about three ounces and a half of extract. It should be kept soft, so as to be fit for forming pills, and hard, so that it may be reduced to powder.

Extractum Colocynthidis. L. This extract is much milder, although less powerful, than the pulp; Dose, grs. v to ʒss. It soon becomes hard and mouldy.^[500]

Extractum Gentianæ. L.E.D. The bitter principle suffers no deterioration in the process: it is used principally as a vehicle for metallic preparations. Form. 36, 53, 103. Dose, gr. x to ℈j.

Extractum Glycyrrhizæ. L.D. It is usually imported from Spain; in the coarser kinds, the pulps of various plums and of prunes are added; it should dissolve in water without leaving any feculence.^[501]

Extractum Hæmatoxyli. L.E.D. The astringent properties of the logwood are preserved in the extract, but it becomes so extremely hard, that pills made of it very commonly pass through the body without undergoing the least change. Dose, grs. x to ʒss dissolved in cinnamon water: it sometimes imparts a bloody hue to the urine of those who have taken it.

Extractum Humuli. L. The bitter taste of the hop characterises this preparation; whether it possesses, or not, any anodyne properties, seems very doubtful. Dose, grs. v to ℈j.

Extractum Opii. L.D. As it contains less resinous matter than crude opium, it is supposed to produce its effects with less subsequent derangement. See Opium. Dose, gr. j to v, for an adult.

Extractum Papaveris. L.D. It is a weak opium. Dose, grs. ij to ℈j.

Extractum Sarsaparillæ. Notwithstanding the reputation which this preparation has acquired, it is very doubtful whether it possesses any medicinal powers. Dose, gr. x to ʒj in pills, or dissolved in the decoction.

Extractum Stramonii. This extract was first recommended by Stöerck, as a powerful remedy in maniacal affections; its probable value in such diseases appears to have been suggested by a very curious process of reasoning, viz. that as it deranged the intellect of the sane, it might possibly correct that of the insane. Experience has certainly not confirmed the very sanguine report of Stöerck with regard to its powers, but it has satisfactorily shewn its occasional value in violent paroxysms, in quieting the mind, and procuring rest. I am informed by my friend Dr. Davy, that, for such an object, it has been very frequently and successfully given, in the Lunatic Military Hospital at Fort Clarence. He farther states that he has himself made many trials with the extract of Stramonium, prepared by Mr. Barry (in vacuo) as well as with the common extract; and that he finds the former to be uniformly more powerful. “In most diseases,” says he, “this medicine would seem uncertain in its operation, sometimes occasioning an anodyne effect, and, at other times, producing irritation, and preventing sleep; I have, however, seen very beneficial effects from it in asthma, and in coughs that have a nightly exacerbation, in doses of from gr. 1/4 to gr. 2, daily.”

Extractum Taraxaci. L.D. The medicinal powers of Dandelion are asserted to exist unimpaired in this preparation, but it becomes inert by keeping. See Taraxacum. Dose. grs. x to ʒj, in combination with sulphate of potass.

These may contain, with the exception of gum, all the ingredients contained in watery extracts, besides resin; their composition however will greatly depend upon the strength of the spirit employed as the solvent; but of this I shall speak more fully under the article Tincture.

Extractum Cinchonæ Resinosum. L.E.D. The operation of spirit in this preparation is two-fold; it extracts from the bark the element which is insoluble in water, and it diminishes the tendency in the extractive matter to absorb oxygen during the process. Dose, grs. x to xxx. It is said that a spurious extract of bark is to be met with in the market, consisting of the extract of the horse-chesnut tree bark, and yellow resin.

Extractum Colocynthidis compositum. L.D. Extract. Catharticum. P.L. 1775. Pilulæ Rudii. P.L. 1720. This preparation has been established through successive pharmacopœias, and has undergone some modification in each; in the present edition the soap has been restored, and its solubility is thereby increased, as well as its mildness as a cathartic. The omission of this ingredient was formerly suggested by the consideration of its being incompatible with Calomel; this however is not the case. It presents a combination of purgative substances which is highly judicious, and will be found to be more powerful than an equivalent dose of any one of the ingredients. Dose, gr. v to ʒss, Form. 71, 81, 88.

Extractum Jalapæ. L.E.D. It is purgative, but is liable to gripe, unless it be triturated with sugar and almonds, or mucilage, so as to form an emulsion. Dose, grs. x to ℈j.

Extractum Rhei. L. The powers of the Rhubarb are considerably impaired in this extract. Dose, grs. x to ʒss. Form. 78.

These preparations are obtained by expressing the juices from fresh plants, and evaporating them in a water-bath; they are generally of a lighter colour than common extracts, and they are certainly much more active, although there is a great difference in the activity of different samples; and perhaps the medicinal powers of the juices themselves are very much under the controul of soil and season. That they vary in quantity from such causes we have ample proof; thus in moist seasons, Beaumé obtained five pounds of inspissated juice from thirty pounds of elder berries, whereas, in dry seasons, he could rarely get more than two. From hemlock he procured in October, 1796, 7·5 per cent. of inspissated juice, and in May of the same year only 3·7; on the contrary, in August, 1768, 4 per cent., and in May, 1776, as much as 6·5; but in general, the product in the autumnal months was the most considerable.

The modes of preparing the inspissated juices of the same plant vary in the different pharmacopœias, and in several points that are very essential; some direct the expressed juices to be immediately inspissated, others allow them to undergo a slight degree of fermentation, and some defecate them, before they proceed to their inspissation.

Extractum (Succus Spissatus. E.) Aconiti. L.E. The medicinal properties of this preparation are analogous to those of the recent Wolfsbane, viz. narcotic, and in some cases diuretic, (see Form. 128.) It is however rarely used. Dose, at first, should not exceed gr. ½, but it may be gradually increased. I have not yet, says Dr. Davy, in a letter recently received from him, had much experience of the Extractum Aconiti, but that little is favourable to its use; “in some cases of chronic rheumatism, and in some of intermittent fever, complicated with visceral disease, it has had a beneficial effect not to be mistaken; the dose has been from one to two grains.” Dr. Stöerck, who first tried this medicine, observed from it a powerful diaphoretic effect; this, says Dr. Davy, “I have not noticed, and yet the extract which I have used was prepared by Mr. Barry, in vacuo, which is certainly far more powerful than that employed by Stöerck; the latter, when applied to the tongue, “levissimam tantum titillationem excitabat,” whereas that of Mr. Barry produces a most disagreeable sensation of burning, which extends to the throat; and in one instance, when applied to the tip of my tongue, it occasioned ulceration.”

Extractum Belladonnæ. L.E. See Belladonnæ Folia. Dose, gr. j, gradually increased to gr. v, in the form of pill. Dr. Davy has made a few trials of Barry’s Extract; the results of which he informs me are not at all favourable to the use of this medicine; it is much more powerful than the common extract, and can only be given with safety in small doses; “in several instances,” says he, “I have not been able to repeat a grain dose daily, more than thrice, on account of the alarming symptoms produced, as head-ache, vertigo, indistinct vision with dilated pupil, and, in one case, irritation of the bladder, occasioning very frequent micturition; in chronic rheumatism and catarrh, with severe cough, the only diseases in which I have yet given it, it has not appeared to be in the least serviceable; it may probably prove valuable to the oculist; from trials that have been made of it here by Mr. Miller, Assistant Surgeon to the Forces, it has been found to dilate the pupil beyond the common extract. Stöerck even introduced his extract into the eye with impunity. Acrid as the preparation is which I have used, the patients have never complained of it, nor have I known any disagreeable effects from it, when applied in solution, sufficiently dilute.”

Extractum (Succus Spissatus. E.D.) Conii. L. Much of this extract, as it is found in commerce, has not been prepared with equal fidelity, nor with due attention to the season when the plant is in its greatest perfection; Dr. Fothergill says, “I know from repeated experiments, that the extract which has been prepared from hemlock, before the plant arrives at maturity, is much inferior to that which is made when the plant has acquired its full vigour, and is rather on the verge of decline: just when the flowers fade, the rudiments of the seeds become observable, and the habit of the plant inclines to yellow, is the proper time to collect it;” the plants which grow in places exposed to the sun should be selected, as being more virose than those that grow in the shade: still however with every precaution, it will always be uncertain in strength. Orfila found that an extract prepared by boiling the dried powder in water, and evaporating the decoction, was inert; in fact, the whole of the activity of the plant resides in a resinous element insoluble in water, and for which I have proposed the name of Conein. Extract of hemlock, when judiciously prepared, is a very valuable sedative; I state this from ample experience, and when combined with Hyoscyamus, and adapted by means of mucilage and syrup, to the form of a mixture, it affords a more effectual palliative than any remedy with which I am acquainted, for coughs and pulmonary irritation. Form. 19. is that from which I have derived the greatest benefit in such cases. See also Form. 2, 3, 4, 19, 57. Since the fourth edition of the present work, I requested my friend Dr. John Davy to make trial of its efficacy in the Military Hospital at Chatham, and I here introduce his report upon the subject;—“My experience of the effects of the Extractum Conii perfectly agrees with that of Dr. Paris, as stated in the fourth edition of the Pharmacologia, and I am of his opinion that when properly prepared, and administered, it is a very valuable sedative; I have given it to the extent daily of from a scruple to a drachm, in chronic catarrh, and in phthisis pulmonalis, either alone or in conjunction with the Extract of Hyoscyamus, and it has afforded more relief than any other medicine that I have tried. From two or three trials of it in pneumonia, I am disposed to think it may be very serviceable in certain forms of this disease, in which venesection is contra-indicated by extreme debility; and also in measles. In the trials alluded to, I commenced giving it in the large dose of a drachm, daily, suspended in water containing in solution a grain of Antimonium Tartarizatum. In a very few instances, where I have from the commencement given it in a large dose, as from ʒj to ʒiss, it has occasioned hallucination of ideas, which in two cases was attended with excitement of the sensorium and increased action of the heart, and in one case, with diminished activity of both. The Extract of Conium, prepared by Mr. Barry, is the most powerful one I have ever used, indeed, until I tried it, I had no just idea of the virtues of Conium as a medicine; but I am now disposed to give credit to Stöerk’s account of its efficacy in various chronic diseases; and I have no doubt but that this valuable medicine has fallen into comparative disrepute and disuse from the bad quality of the extract commonly employed.” Dr. Maton has found that the value of this extract is greatly increased by including the seeds in its preparation. Dose, grs. v to ℈j; or more, twice or thrice a day; in a full dose it produces giddiness, a slight nausea, and a tremor of the body; a peculiar heavy sensation is also experienced about the eyes; and the bowels become gently relaxed: unless some of these sensations are produced, we are never sure that the remedy has had a fair trial of its effects. Patients will generally bear a larger dose at night than at noon, and at noon than in the morning.

Extractum Elaterii. L. This substance spontaneously subsides from the juice of the wild cucumber, in consequence I presume of one of those series of changes which vegetable matter is perpetually undergoing, although we are hitherto unable to express them by any known chemical law. It is therefore not an extract, either in the chemical or pharmaceutical acceptation of the term, nor an inspissated juice, nor is it a fecula,^[502] as it has been termed; the Dublin College has perhaps been more correct in simply calling it Elaterium, the name given to it by Dioscorides.

It occurs in commerce in little thin cakes, or broken pieces, bearing the impression of the muslin upon which it has been dried; its colour is greenish, its taste bitter, and somewhat acrid; and when tolerably pure, it is light, pulverulent, and inflammable.

The early history of this medicinal substance is involved in great perplexity, each author speaking of a different preparation by the same name; for instance, the Elaterium of Dioscorides must have been a very different substance from that of Theophrastus; and, wherever Hippocrates mentions the term, he evidently alludes to any violent purgative. “Hippocrati Elaterium medicamentum est quod per alvum expurgat.” (Bod: in Theophrast.) This will, in some degree, reconcile the discordant testimonies of different authors with regard to the powers of Elaterium; for example, Dioscorides states its dose to be from grs. ii to ℈j—in Ætius, Paulus, and Actuarius, it is recommended to the extent of ʒss—in Mesue from ℈ss to ℈j—in Bontius (Med: Ind:) from ℈j to ʒss—Massarias exhibits it in doses of gr. vj—Fernelius and Sennertus to ℈j—Herman from grs. v vj—Quincy to grs. v—and Boerhaave does not venture to give more than gr. iv—while the practitioners of the present day limit their dose from gr. ½ to grs. ij. Dr. Clutterbuck, with a laudable intention to discover some method of procuring this article at a cheaper rate, and at the same time of establishing some process which might ensure a preparation of more uniform strength, has lately performed a series of interesting and instructive experiments,^[503] the results of which prove in a satisfactory manner “that the active principle of this plant is neither lodged in the roots, leaves, flowers, nor stalks, in any considerable quantity: nor is it to be found in the body of the fruit itself, or in the seeds, but in the juice around the seeds; the substance which spontaneously subsides from this liquor, obtained without pressure, is genuine Elaterium, the quantity of which, contained in the fruit, is extremely small, for Dr. Clutterbuck obtained only six grains from forty cucumbers.” This gentleman communicated the detail of these experiments to the President of the College of Physicians, who requested me, as professor of Materia Medica, to report upon them. I accordingly deemed it to be my duty to enter upon a series of new experiments, which I have lately completed, with the able assistance of Mr. Faraday, in the laboratory of the Royal Institution. The results of which will shew, that although Dr. Clutterbuck found that an eighth part of a grain of elaterium seldom failed to purge violently, yet, strange as it may appear, that not more than one grain in ten of elaterium, as it occurs in commerce, possesses any active properties, and that this decimal part is a vegetable proximate principle, not hitherto noticed, to which I shall give the name of Elatin. I shall subjoin the detail of my experiments, and I think it will appear that their results will authorise me to express the chemical composition of Elaterium in the following manner.