OF OPIUM.

The Ancients having Experienced that Opium would oftentimes Kill, though taken in no large quantity, ranked It with Poisons, and gave It the first place among Those, which from their Stupefying Quality They call’d Narcotic.

True indeed it is, that We do every Day find This to be, in a small Dose, one of the most Noble Remedies in the World. But it is not worth the while to engage in the Controversie warmly debated by some Authors, how far Poisons are Medicinal; since it is notorious enough, that Medicines do sometimes prove Poisonous. And take the Matter as We please, it may serve to very good Purposes to understand the manner of Operation of so Celebrated a Drug, and help Us in a great Measure to ascertain Its Use in different Cases, if we are beforehand rightly apprised of Its Nature and Way of Acting.

In order hereunto, it is necessary, besides some other PrÆcognita, since one of the chief Virtues of this Medicine Is Hypnotic, to Define distinctly what Sleep is, or rather, (to avoid Confusion and Disputes about Words) what Difference there is between an Animal Body when asleep and when awake. For I suppose the History, Manner of Preparing, &c. of Opium, to be already sufficiently known.

First then, There is no One but knows that in Sleep there is a Cessation from Action. When Waking, We Walk, Discourse, Move this or that Limb, &c. but in natural and undisturbed Rest there is nothing of all These; that is, whereas being awake, We do perform several Motions by the voluntary Contraction of our Muscles; when asleep, those Muscles only are Contracted, whose Action is in a manner Involuntary, or to which the Mind has always so constantly determin’d the Spirits, that It does it by a Habit, without the Intervention of the Reasoning Faculty; such are Those of the Heart and Breast.

So that there is at this time a kind of Relaxation or Loosness of the moving Fibres of the several Members; or at least such a quiet Position and State of them, by which all the Antagonist Muscles are in an Æquilbrium and Equality of Action, not overpowering one another. For this indeed seems to be one great Design of Sleep, to recover to the Parts overstretched by Labour their former Tone and Force; and therefore we do naturally, when composing our selves to Rest, put our Body into that Posture which does most Favour the particularly wearied Limbs, and conduce to this end.

In the next place, it is very plain that there is in Sleep not only a Rest and Suspension from Acting of most of our Bodily Organs, but even of our Thinking Faculty too. That is (for I would prevent Cavils) a ceasing from such Thoughts as when Waking We are exercised about, which we do Reflect upon, and Will to employ our Mind with. For though Dreams are Thoughts, yet they are but imperfect and incoherent Ones, and are indeed either so faint and languid Representations, as to be consistent with our Sleep, as some may be; or else if they be strong and lively, they are, as every one knows, the Interruption and Disturbance of It.

From hence It will follow, That the Motion of the Arterial Fluid must be, Ceteris Paribus, more sedate, even and regular, in the time of Sleeping than Waking; For, besides the various Alterations which in the latter State this receives from the several Passions of the Mind, the very Contractions of the Muscles themselves in Exercises of the Body do differently forward its Course; whereas in Sleep the force of the Heart and Pectoral Muscles being more constant and uniform, gives it a more calm and equally continued Impulse.

Hence also it will come to pass, that the Influx of the Liquor of the Nerves into the Organs of the Body, as also Its Reflux towards the Brain, is in Sleep either none, or very inconsiderable; that is, that this Fluid has at this time but little or no Motion. For ’tis Muscular Action and Sensation that require It to be thus determin’d, this way or that, which are now hardly any. And yet by the arrival of Blood at the Brain, this Juice will still be separated there, fit to be derived into its Canals or Tubes. So that by this means there will be a kind of Accumulation, or laying up in Store, of Spirits for the Offices and Requirements of Waking.

Thus We may in short look upon the time of Watching, as the time of Wearing out, or the Destruction of the Animal Fabrick; and the time of Sleep, as that in which it is repaired and recruited; not only upon the account of what We have just mentioned concerning the Nervous Liquor, but also with respect to all the other Parts, as well Fluid as Solid. For Action does necessarily by Degrees impair the Springs and Organs; and in Motion something is continually abraded and struck off from the Distractile Fibres, which cannot otherwise be restored than by their being at rest from Tension. Besides that, such a regular and steady Course of the Blood, as we have observed to be in Sleep, is by far more fit and proper for Nutrition, or an Apposition of Parts to the Vessels, which an uneven Hurry of It is more apt to tear off and wash away.

The Case being thus, it is very plain that whatsoever can induce such a Disposition of the Fluids and Muscular Parts of the Body, as this We have described, will so far cause Sleepiness. And in like manner, when any thing interposes and hinders this Composedness and Tranquillity, the removing of the Impediment will be the causing of Sleep; inasmuch as this is only reducing the Animal Œconomy to its right State, in which by natural Order there must be a Succession of Sleeping and Waking.

Thus it appears how necessarily continued Exercises do make Us Sleepy, since These do exhaust the Juice of the Nerves; that is, both lessen its Influx into the Organs of Motion, and incline the Mind not to determine it any longer that way, upon the account of the Pain and Uneasiness, with which too violent a Tension of the Parst is always attended; which therefore we must needs desire to Relax, or lay to Rest.

That Sleepiness which follows upon a fulness of the Stomach after Eating or Drinking, is owing to a different Cause; and does indeed so nearly fall in with the Effects of Opiate Medicines, that it requires a particular Consideration.

As Hunger, or the Emptiness of the Stomach, is a painful Sensation; so the satisfying or removing of This, is a pleasing or agreeable One. Now all Pain is a Stimulus upon the Part affected; and This, we all know, being attended with Contractions of the pained Membranes, causes a greater Afflux than ordinary of the Nervous Juice that way. On the other Hand, Pleasure, or a delightful Sensation in any part, is accompanied with a smooth Undulation, and easie Reflux of the Liquor of the Nerves towards the Brain. This is, as it were, the Entertainment of the Mind, with which being Taken up, it does not Determine the Spirits to the Organs of Motion; That is, there is such a Relaxation of the Muscular Fibres, and such a Disposition of the Nervous Fluid, as we have observed to be necessary to Sleep.

This is the Reason of that Chilliness in the Limbs, which we commonly Complain of after a good Feast.

If it seem strange that a Pleasure in the Stomach should so powerfully Influence the Mind; let it be considered, on the other Hand, how violent Effects, an uneasie and disagreeable Sense in the same Part does produce; what a terrible Agony Two or Three Grains of Crocus Metallorum throws the whole Fabrick into; how readily the Fluid of the Nerves is with a more than Ordinary Impetus determin’d and commanded into the Muscles of the Stomach and Abdomen, in order to throw off the Enemy, and remove the ungrateful Sensation.

Now the Consequences which we have ascribed to a pleasing Sense in this Part, are only just the contrary of these we find the opposite Affection of Pain induces. And indeed Pleasure and Pain are Two great Springs of Action in the Animal Œconomy; The Changes they make in the Fabrick are the Causes of many Effects which seem surprising, because we do not regard the Mechanism by which they are produced: but these must be more considerable in the Stomach than any where else; This Part being, for very wise Purposes, of so acute a Feeling, that some Philosophers have for this Reason thought It to be the Seat of the Soul.

Besides this Consideration, We must take notice that, the Stomach being distended with Food, presses upon the descending Trunk of the Aorta, and thus causes a greater Fulness of the Vessels in the upper Parts; whereupon the Brain is loaded, or the Derivation of Spirits into the Nerves diminished, and Unactivity or Drowsiness insues. From hence proceed Those Flushings in the Face, Redness, &c. after plentiful Eating or Drinking, most Visible in Those whose Vessels are Lax and Weak, as in Exhausted and Hectick Persons they more especially are.

Thus we may, without the Assistance of the New Chyle entring into the Vessels, account for that Inclination to Sleep which follows upon a full Stomach; Tho’ we must also allow the Distension from This to be a considerable Cause of the same Effect; But this does not happen immediately, nay, sometimes perhaps not within Two or Three Hours after Eating; and therefore the sudden Drowsiness must (as well as the present Refreshment and Reviving which Meat gives) be chiefly owing to some more speedy Alteration.

We come then in the next Place to Opium it self; The Chymical Analysis of which (147) does out of One Pound afford of a Volatile Spirit of the like Nature with that drawn from Harts-horn, Five Ounces and Five Drachms; of a fÆtid Oil, One Ounce Two Drachms and a half; of Caput Mortuum, smelling like Spirit of Harts-horn, Seven Ounces and Six Drachms.

The Virtues therefore of Opium are owing to a volatile Alcaline Salt, intimately mixt and combin’d with an Oily, Sulphureous Substance. The Effects of which We must consider, first of all upon the Stomach, and afterwards, when they have passed the PrimÆ ViÆ, upon the Arterial Fluid it self.

An agreeable Sensation produced in the Stomach, together with a Distension of Its Membranes, we observed before to be the Cause of that Sleepiness to which we are so prone after Eating. The One of These ingages the Mind, the Other acts upon the Body. For Pleasure amuses the Soul, as it were, so that It does not Think, or exercise it self about any outward Objects; that is, Is inclined to Rest. And the Fulness of the Vessels in the Brain Checks and Hinders, in some Measure, the Derivation of the Nervous Juice into the Organs, &c.

Now They who take a moderate Dose of Opium, especially if not long accustomed to It, are so Transported with the pleasing Sense It induces, that They are, as They oftentimes express themselves, in Heaven; and tho’ They do not always Sleep, (which proceeds from the Presentation of pleasing Images to the Mind being so strong, that like Dreams they do over-ingage the Fancy, and so interrupt the State of Rest) yet they do however injoy so perfect an Indolence and Quiet, that no Happiness in the World can surpass the Charms of this agreable Extasie.

Thus We have from this Medicine, but in a far more eminent Degree, all those Effects which we observed to follow upon that grateful Sense in the Stomach, which a moderate Fulness produces. For no Bodies are so fit and able pleasingly to affect our sensile Membranes, as Those which consist of Volatile Parts, whose activity is tempered and allayed by the smoothness of some Lubricating and Oily ones; which by lightly Rarefying the Juices of the Stomach, and causing a pleasant Titillation of Its Nervous Coat, will induce an agreable Plenitude, and entertain the Mind with Ideas of Satisfaction and Delight.

The Case being thus, We easily see upon what Mechanism the other Virtues of Opium do depend, Its Easing Pains, Checking Evacuations, &c. not only in that the Mind being taken up with a pleasing Sense, is diverted from a disagreable One; But all Pain being attended with a Contraction of the Part, That Relaxation of the Fibres which is now caused, eludes and destroys the Force of the Stimulus.

In like manner in immoderate Secretions there is most commonly an Irritation of the Organs, the Removal of which will abate the Discharge. And herein lies the Incrassating Quality of this Medicine, in that the Twitching Sense upon the Membranes of the Lungs, Bowels, &c. being now lessened, the sharp Humor is suffered to lodge there in a greater quantity, before it is so troublesome as to be thrown off and expell’d; it being all one as if there were no Irritation of the Part, if the uneasie Sense thereof be not regarded by the Mind.

These Effects will all be heightened by the Mixture of the Opiate Particles with the Blood; Which is hereupon Rarefied, and Distends its Vessels, especially those of the Brain; and thus does still to a greater Degree lessen the Influx of the Nervous Fluid to the Parts, by pressing upon the little Tubuli, or Canals, thro’ which it is derived.

This is the Reason of that Difficulty of Breathing, which they do for a time Experience who take these kind of Medicines; This Symptom being inseparable from the Rarefaction of the Blood in the Lungs.

From hence it appears, that the Action of Opium is very Analogous to that of other Volatile Spirits, only that a small Portion of It has a force equal to that of a greater quantity of most of Them.

This is very evident in Those who accustom Themselves to take large Doses of It; as the Turks and Persians do to that Degree, that it is no uncommon thing there to Eat a Drachm or Two at a time; for the Effects of It in Them are no other than downright Drunkenness; upon which account (148) it is as common a Saying with Them, and on the same Occasion, He has eat Opium; as with Us, He has drank too much Wine.

Neither indeed do They otherwise bear such large quantities of It, than our Tipplers will a great deal of Brandy; that is, by habituating themselves to It by degrees, beginning with small Doses, and requiring still more and more to raise themselves to the same Pitch. Just as Galen (149) tells Us of a Woman at Athens, who by a gradual Use had brought her self to Take, without any hurt, a considerable quantity of Cicuta or Hemlock. Which Instance is the more to our Purpose, because Nic. Fontanus (150) knew one who being Recovered of the Plague, and wanting Sleep, did, with very good Effect, eat Hemlock for some time, till falling Ill again of a Fever, and having left off the Use of this Remedy, He indeavoured to procure Rest by repeated Doses of Opium, which (Nature having been accustomed to a stronger Alterative) had no Operation, till the help of Cicuta was again call’d in with desired Success.

It is a sufficient Confirmation of all this Reasoning, that Prosper Alpinus (151) observed among the Egyptians, those who had been accustom’d to Opium, and were faint and languid thro’ want of It, (as Drinkers are if they have not their Spirits) to be recovered, and put into the same State of Indolence and Pleasure, by large Doses of Cretic Wine made hotter by the Infusion of Pepper, and the like strong Aromatics.

Nor is it perhaps amiss to remark, that in Maniacal People, as is frequently observ’d, a Quadruple Dose of Opium will scarce produce any considerable Effect: Now in Persons so affected, the Mind is deeply ingaged and taken up with some Images or other, as Love, Anger, &c. so that it is not to be so easily moved or diverted by those pleasing Representations which it would attend to at another time, and upon which the Virtues of this Medicine do in a great measure depend. Besides this, those who are Maniacal do to a Wonder bear the Injuries of Cold, Hunger, &c. and have a prodigious degree of Muscular Force, which argues the Texture of their Blood to be very strong, and the CohÆsion of its Globules great; so that the Spirituous Parts of the Opiate cannot make that Disjunction and Rarefaction of this Fluid in Them, which it does in ordinary Bodies and Constitutions.

Many are the Immprovements which might be made of this Theory, with relation to the Practice of Physick; but these will be obvious enough to one instructed in the Animal Œconomy.

To conclude then as to the Subject in Hand, it is very plain that there needs no more to make Opium prove Destructive or a Poison, than to take too great a quantity of It; for then It must Inflame the Stomach, and Rarefie the Blood to such a Degree, that the Vessels cannot again recover their Tone, whereupon Apoplectic Symptoms, &c. will insue.

To be convinced of this, I forced into the Stomach of a small Dog about half a Drachm of Crude Opium dissolved in Boiling Water. He quickly Vomited It up with a great quantity of Frothy Spittle; but repeating the Trial, by holding up his Head, and beating him, I made him retain Three or Four Doses, intermitting between each about a quarter of an Hour; when he had thus taken, as I could guess, near Two Drachms, I watch’d him about an Hour, then he began to Sleep, but presently started up with Convulsions, fell into universal Tremblings, his Head constantly twitch’d and shaking, he breath’d short and with labour, lost intirely the Use first of his hinder Legs, and then of the fore ones, which were stiff and rigid like Sticks. As he lay Snorting, to hasten his End, I was giving him more of the Solution, but on a sudden his Limbs grew limber, and He Died.

Opening his Stomach, I found It wonderfully distended, tho’ empty of every thing but some Water and Opium; parcels of Frothy Mucus swimming in It; the inside was as clean as if scraped and washed from all the Slime of the Glands, with some Redness here and there, as in a beginning Inflammation. The Pylorus was Contracted. The Blood-Vessels of the Brain were very full; and I took out a large Grume of Concrete Blood from the upper part of It, cutting into the Sinus Longitudinalis, as is not uncommon in Apoplectic Carcasses; but found no extravasated Serum in the Ventricles, nor among any of the Membranes.

As to the Cure of such a Case; besides other Evacuations, Acid Medicines and Lixivial Salts must certainly do Service; these by their Diuretic force causing a Depletion of the Vessels. This is the Foundation upon which Starky compounded his Pacific Pill. Generous Wine, which the Ancients gave for an Antidote, can be no other ways useful, than as It dissolves the Resinous Clammy Part of the Opium sticking to the Coats of the Stomach, and so forwards its Expulsion by other Helps, which cause a Contraction of the Muscular Fibres.