Part 13

‘BUT if these subtile and active Particles be of that Nature, that they can penetrate the Pores of other Animals, and occasion a like Coagulation of their Blood, not only Men, but Brutes also, will be seized with a _Pestilence_; but this does not always very necessarily happen; because the Blood of Animals is different from humane Blood, so that although these Particles are supposed to get into it, it does not therefore necessarily follow that they must vitiate it, any more than will _Aqua Regia_ dissolve all kinds of Metals; but yet Brutes of all kinds, or some of them only, will be seized equally with Men, when this subtile and active Ferment, which penetrates the Surface, is of that Nature, as will taint the Blood of other Animals with those _pestilential_ Requisites.

‘AS this kind of Contagion then can easily proceed from an infected Person at a great Distance, as often as the noxious Particles can reach another Person, and give that Degree of Coagulation and Fusion, as is necessary to a _Pestilence_; the more aggravated then will be this Calamity, and more easily spread, when a healthful Person is near to one already infected; and yet much more worse, if it is in Contact with those Parts, which more plentifully, and with a greater _Impetus_, breath out infected Steams, as if the Air arising from the Mouth and Lungs, which must be extreamly hot, or the Perspiration of a Carbuncle when it is greatly inflamed; for in this Case the exhaling Particles will be in their greatest Activity when nearest the recipient Body, and likewise more dense, that is, more numerous, and consequently of greatest Efficacy.

‘BUT it is not every one that is seized with a _Pestilence_ from Contagion, by Means of Steams exhaling from any particular Parts of the Body; but only when these Steams, and the Air it self, hath joined with, and interspersed through it Particles of vitiated Faculties; and then this Kind of Fever will easily be communicated, and necessarily ensue, not only on Account of what gets into the Body with the inspired Air, but because also the whole Body is surrounded with such an Infection, wherein the noxious Particles floating about on all Sides, will endeavour to penetrate through the Pores upon the Surface, and get that Way into the Blood; for although the Skin is thicker upon the Surface of the Body, than that Pellicle covering the Vessels in the Lungs, and for that Reason it requires longer Time for such Particles to get that Way into the Blood, and the Habit of the Body, yet it is no Argument that they cannot get that Way at all, and be admitted into the Juices.’

BY this we are able to gather, that when a Fever from some Faults in the _Non-naturals_ comes to the highest Degree of Malignity, it makes such a Change in the animal Fluids as renders some Parts of them poisonous, and capable of exciting the like fermentative Motions, wheresoever they come into a proper Subject, without any of those procatarctic Causes as gave Rise to the Fever of the first Person seized.

OF what Nature then this Poison is we may conjecture from the Circumstances of its Production. All animal Bodies do more or less generate a Salt; or rather, in Proportion to the Strength of their digestive Powers, do they more or less subtilize the saline Particles which are taken in with their necessary Nourishment. This is abundantly manifest in the Distillation of many animal Substances, which plentifully yield a volatile Salt. But indeed in the Composition of this, in a natural and healthful State, there is joined a very subtilized Sulphur or Oil; which contempers and softens it into a Fitness for the Purposes of the OEconomy: And under this Modification, it becomes the Principle of Vitality, and the chief Instrument of animal Action; not unlike what this is conceived to be, is the common _Sal volatile oleosum_, or any other Spirits drawn from odorous Bodies.

IT matters not what Names Persons please to distinguish this by, in an humane Body; but that somewhat of this Kind is naturally the Produce of its digestive Powers, in the highest Degree of Comminution or Subtilization they are capable of bringing any Thing to, no one will question; and that those minute Threads or Fibres, of which the whole is a Composition, are animated by it; or, to speak more strictly, owe to it their Elasticity and motive Faculties.

IT is hoped, that no one who hath been accustomed to Reasonings of this Nature, will find any Difficulty in conceiving such a Difference of Principles, so finely blended together, as here suggested of a saline, and an oleous, or humid Substance: And whosoever reads _Bellini_, or any others who have wrote in the same Manner, will find continual Regard had to those two Principles, even in the animal Spirits; for without it there can be no Notion had of what is so frequently mentioned, and which by their Effects we find must be true of them, that they are too dry, hot, active, fiery, and the like; or too humid, vapid, sluggish, viscid, _&c._ And it is further equally manifest, that in Proportion to the greater or lesser Degrees of Motion in those Fluids, from whence this subtile Composition is generated, and the Concussions of those fine Threads into which it is separated, will it err in one or other of the foregoing Extremes.

IN a Fever therefore, where the animal Fluids are in the highest Degree of Agitation, and from Causes too of a coagulating Nature, it ought to be no Wonder that even this subtile Union should be in some Measure dissolved, and the softer and more humid Parts broke and exhaled, so much as to leave the more rigid and saline ones not only unfit to lubricate those Elastick Threads, wherein they reside, but sharp and pointed enough to stimulate, contract, and harden them into all Loss of Motion.

AS the Destruction likewise of this _Nexus_ in so subtile a Fluid leaves the saline Parts capable of injuring even that OEconomy which gave it Existence, so may its Volatility favour its Escape in a great Measure by Transpiration, so as to affect also other Persons within its Reach; and These with all other Particles of like Nature, which, by an Over-Agitation, and fermentative Motion of the animal Fluids, are separated from the softer and lubricating Compositions with which they were naturally joined, and which by their Volatility transpire and float in the Air, we take to be the true _contagious Miasmata_, that convey, propagate, and continue a _Pestilence_, after the Cause first raising it ceases.

NOR will this seem strange to any who are accustomed to reflect, how many Substances are changeable into a poisonous Nature, which before were not only inoffensive, but useful to the Purposes of Life. Some Minerals, whose saline Parts in their Production are naturally blended with good Quantities of Sulphur, are harmless, and good _Alterants_; but when by any Means those Principles are separated, the saline Parts become strong _Emeticks_ and _Catharticks_, even to the Degree of a Poison. Who does not know that _Antimony_ may be taken crude in large Quantities without any manifest Effect, but that the Chymist can take somewhat from it, that in few Grains shall operate beyond the Power of a strong Constitution to bear?

THOSE Arrows of Death therefore that make such dreadful Slaughter in a _Contagion_, are the animal Salts of infected Persons, set loose from their natural Combinations, and subtilized into the highest Degree of Volatility, by the Agitation and fermentative Motion of a Fever. And the Buboes, Carbuncles, _&c._ in a _Pestilence_, are nothing else but Collections of Particles, or Coalescences, formed in such irregular Motions, and thrown out of the Course of Circulation by those necessary Laws whereby every Thing is rejected, that cannot be assimilated into homogeneous and like Properties: The Matter of which Excretions is likewise of so subtile and fermenting a Nature, that if introduced into the Fluids of another well Person, it excites there the same Motion and Disorder.

THIS change of animal Substances into a Poison, is too common a Truth to want any Attestation to those who have been but indifferently conversant in Natural Enquiries. And it is greatly to our Purpose, that even those Creatures, which are generally deemed poisonous, do require certain Degrees of Heat, and animal Action, to exalt their Juices to so high a Degree of Volatility, as to put on the Properties of a Poison, and act as such upon other living Creatures; insomuch that it is not only a common Observation that these Animals lose their poisonous Nature when remov’d into Climes colder than what is natural to them, but that also they are not so venomous in their own Climates, at the cooler Seasons of the Year, as in the most sultry.

BUT the Case of a mad Dog entirely comes up to that of a _Contagion_ from a Fever. When the hotter Seasons of the Year throw that Creature into Madness, it is manifestly from a great Increase of Velocity and Motion in the Fluids, which brings on what is equivalent to a _Delirium_, by an additional _Impetus_ upon the Brain, and for want of so much Room through the Skin for Transpiration, as in other Animals; the chief Evacuation is by the Glands of the Mouth: That is, in short, the Dog hath a Fever, which breaks the natural Texture of the Juices, disengages and subtilizes the more rigid or saline Parts, and critically discharges them by the most convenient Outlets the Creature is furnished with, changed into such a poisonous Nature, that wheresoever they come to mix with the Juices of others, they excite in them the like inordinate and mischievous Alterations.

THIS Theory likewise might be further illustrated by many Instances from inanimated Fluids, which are capable of being put into Fermentation by a very small Portion of Matter, and which shall by such an Agitation from new Particles, or _Moleculæ_ having Properties of communicating the same Effects to another quiescent Fluid; not much unlike what we see in the Communication and Propagation of Fire, which is excited and carried on in proper Subjects from the minutest Beginnings, and increasing also in its own Force as it spreads.

WHEN a Person therefore falls into a Fever from any epidemic, or other more private Cause, and that Fever rises to such a Degree of Malignity as is always supposed in a _Pestilence_, as far as any _Effluvia_ do exhale from that Person, so far may he be said to have round him a contagious and poisonous _Atmosphere_; because there transpires from him such Particles as will excite in other Animals of like Constitution, the same fermentative Motions as those to which they owe their own Origin.

ALTHOUGH therefore, in the Beginning of epidemical Diseases, and during the Subsistence of their common Causes, particular Regard is to be had to these Causes, and the Manner whereby they affect the People; yet when it is come to this pass, that the Fever it self is productive of a Poison, or somewhat intirely disagreeable, that communicates the same Impressions upon others, without any Concurrence of the first Cause, then such a Fever is truly a Pestilence by Contagion, and all precautionary Regards ought peculiarly to be suited, to prevent its Infection or Spreading; either by keeping the well Subjects clear from the sick, or destroying the Influence of the poisonous Exhalations, or fortifying the sound against it. But to these Ends, it is necessary to have some tolerable Notion of the Manner how these secret Destroyers are continued, and conveyed to great Distances.

THE most common Manner of conveying and spreading a Contagion, observable in the preceding historical Collections, and which also is the Case of our present Apprehensions from Abroad, is by infected Persons, and Merchandize; it being attested by too many Facts to admit of the least Doubt, that even Packs and Bails of Goods carry the poisonous _Miasmata_ about with them; and from the Nature that we here suppose this Poison to be of, nothing is more likely to preserve it than animal Substances, as Hair, Wool, Leather, Skins, _&c._ because the very Manner of its Production, and the Nature of its Origin, seems to give it a greater Affinity with such Substances than any other, and to dispose it to rest therein until by Warmth, or any other Means of Dislodgement, it is put into Motion, and raised again into the ambient Air.

TO know how these _Effluvia_ come to have such fatal Influences over Mankind, and to understand their Progression from the first Seizure, to the End of that Distemper they gave Birth to, requires too many _Precognita_ from the Mechanism of the animal OEconomy, and the Agency of such minute Instruments, to be particular about, in the Compass here limited. And a Reader who is duly fitted for such Enquiries, will find the utmost Satisfaction from _Bellini_ of _Fevers_, and Dr. _Mead_ of _Poisons_; how the Blood, and all the Secretions therefrom, are affected, and changed by such Causes.

WE shall here therefore only suggest some Hints concerning the Suddenness of their Seizure, and their Energy of Operation. And this will not be difficult to conceive by those who are acquainted with that universal Property of Matter, whereby it is more or less determined to draw, and unite again, when separated into Parcels, according to the greater or lesser Affinities of their Figures, Solidities, and Quantities of Motion. As nothing therefore in Nature is supposed to bear a greater Similitude, than in this Case the natural animal Salts do with what hath been subtilized and set on Float in the Air, it can be no Wonder that when the Ambient is sated with the latter, they readily join with the former, as soon as they are received into the Body. And this is supported by the Authority even of _Bellini_, who allows, in the Beginning of his XXVIII_th Proposition_, that the _Antecedents_ to a pestilential Fever do sometimes vitiate the Spirits immediately in Quality.

AS the ordinary Course therefore of producing Fevers is by disordering the Blood first in Quality, with such Mixtures as coagulate it, that is, as make it unequally fluid, some Parts being thinner, and others thicker than natural; so by these extreamly subtile _Effluvia_, in a _Contagion_, the Spirits are destroyed in their natural Texture, and the more rigid and saline Parts, by a Combination with the venomous _Spicula_, changed into Dispositions destructive of that Constitution they were before destined to preserve. Whosoever then considers what must be the necessary Consequences of such an immediate Depravation and Change in that Fluid, which is an absolute Requisite to all animal Action, will not at all wonder at any of the Affections which are commonly enumerated as the _Concomitants_ of a Contagion; and a tolerable Acquaintance with the OEconomy, by the Help especially of the Authors before referred to on _Fevers_ and _Poisons_, will enable any one to account severally for their Production.

THIS then being the Case of a _Contagion_, that a Person having a Fever, critically throws off poisonous _Effluvia_, which were generated during such irregular Motions of the animal Fluids, insomuch as to diffuse for some Distance round, what will infect other Persons within their reach; and that so many have got this Infection, that no Part of the Air, for some Tract of the Country together, is free from them; the poisonous _Atmospheres_, if they may be so termed, of the infected, extending and mixing into one universal, common _Contagion_; this, I say, being the Case here under Examination, why any at all survive, must be owing either to the Goodness of their Constitution, or to proper Means to defend against its Infection, or to conquer it when received; which naturally brings us to consider these two important Ends, of _Preservation_ and _Cure_.

AS for the _First_ of these, the common Experience, of meaner People being mostly carried off, admonishes all to live upon as nutritive and generous a Diet as can be procured; and such Things as not only yeild due Nourishment, but Plenty of Spirits, and what easily perspires. For there are many Things of good Nourishment, that are not easily perspired; such as all light and viscid Substances, as Pork, Fish, and the like, which therefore are very apt to go into Fermentation, and generate Corruption; in short, whatever even the common People have Notions of, as apt to bring Surfeits, ought to be avoided, and such Means of Subsistance complied with, as generate a warm, rich Blood; and in Proportion to the Ways of Living at other Times, should every one, except those who accustom themselves to Riot and Excess, indulge himself at a higher Rate.

ROASTED Meats are by all preferred to boiled, and if Pickles and high Sauces are ever to be encouraged, it is on these Occasions; and _Garlick_, _Shallot_, _Onions_, &c. are extreamly serviceable, and preferable to the hot, dry, spicy Seasonings, because their pungent Volatility seems naturally covered with a Softness, or balsamick Quality, more agreeable to the Nature of animal Spirits. To which Purpose it is very remarkable, that in the Histories of many Pestilences, Notice is frequently taken of the Exemption of _Jews_, and People who deal much in such Fare, from Infection. And it is customary with some experienced Sailors, to lay in great Stores of such Things against their Arrival at infected, and unwholsome Countries.

THERE is also a very strict Regard to be had to the Firmness and Strength of the Solids, which is greatly assisted by moderate Exercises, but carefully avoiding too much, and every Thing that occasions too great an Expence of Spirits at a Time, and particularly by over-Warmth. But to this Purpose I cannot conceive any Thing more serviceable than frequent Immersion in cold Water, so that the Times of staying in are as short as possible, the Good received hereby being chiefly in the first Shudder and Constriction; and it is particularly to be remembred, tho’ the preceding Author hath omitted it, that Watermen, and others, whose Occasions imployed them much upon the River, and in the Cold, suffered least in the late Sickness. The Use of _Vinegar_, and other _Acids_, are also of Service for the like Intention.

YET besides the Helps for this End from common Diet, and Way of Living, Assistances may also be had from Medicinal Preservatives, such as those commonly termed _Antidotes_, consisting of spicy volatile Particles, which afford a natural _Pabulum_ to the animal Spirits, and by carrying into the whole Habit a fine subtle Oil, the better secure them against those Contagions _Spicula_ which are in Readiness to mix with them; and for this Purpose, we are furnished with a most elegant and useful Medicine, since many Authors of Note have wrote on this Subject, which is the _Sal Volatile Oleosum_, if it be well loaded with the essential Oils of Spicy Ingredients; although indeed with some Constitutions more fetid Compositions are very suitable; but they all agree in carrying into the Habit somewhat that both recruits, and guards the Spirits against any foreign Mixture, or from unnatural Separations of their saline and humid Parts. And to the same End, in robust Constitutions, who have been accustomed to fare hard, the Spirit or Oil of Turpentine frequently drank in small Doses might be a great Means to preserve the poorer Sort from Infection.

BECAUSE former Writers on these Occasions have given _Formulæ_ of things of this kind, much more prolix and inelegant than the present Practice is accustomed to, it may not perhaps be unacceptable to give two or three Examples more conformable to the latter. But because I judge such general Prescriptions rather of Prejudice than Service, when they come hastily and inadvertently to be required by the common People, I cannot but think it much better to leave such to be ordered and regulated according to particular Persons Constitutions and Exigencies.

AS to those preservative Means which a Government only have the Power to provide, they must likewise be left to those who have that Power, but, with due Submission to such, it is conceived that removing infected Persons is a much easier and safer Care, than shutting them up in great Towns: And it was certainly the greatest Error committed in the late _Plague_ here, as our Author above grievously complains, to confine the sick and well together.

IT seems a Point yet in Dispute, whether great Fires at such a Time are of Service or hurtful, which to me is somewhat wonderful, because whosoever considers the Necessity for Air in Respiration, and by what Quality it becomes of such real Service to the Preservation of Life, cannot think such Fires proper, because they destroy that very Property in the Air, which is demonstrable by innumerable Experiments. As to the Dissipation indeed of pestilential Vapours, or their Destruction in any Manner, they undoubtedly may do Service, but then that ought to be done at vast Distances only from where People inhabit. And what Fires common Occasions require at such Times, are rather to be made with such Substances as abound with, and yield a nitrous Salt, because that seems to be the chief Support of the vital Property in the Air, and such are our common Coals; for every one knows how much more all Wood-Fires are suffocating, and give a Languor, and Flatness to the Spirits.

PRESERVATIVE Fumigations are largely talked of by all, on these Occasions, and they with good Reason deserve to be practised, because while the Poison is on Float in the Air, it may undoubtedly be entangled so as to lose its Power of acting as such; but then for this Purpose such Things ought to be used as exhale very subtile Sulphurs, as the spicy Drugs and Gums. And on this Account I suspect Wood-Fires to be bad, because they raise into the Air a very gross and viscid Humidity, which is not only very unfit to lay hold on, and unite with, the extreamly minute Agents that are to be provided against, but also carry into the Lungs with the Air in Respiration, such Particles, as dispose of themselves to Viscidities, and such Changes in the Blood, as are the Production of the worst Fevers, without any other co-operating Cause; for the Fire only forces out that Moisture, which, while a Tree is in its Growth, naturally perspires from it; and how an Air so impregnated is like to be of Service against a Pestilence, any one may soon be a Judge, who considers those Kinds of Fevers which are most commonly epidemical in wood-land Countries.

SUCH Drugs however as are from a vegetable Production, and abound with subtile, volatile Parts, are of Service to be exhaled into the Air this way, both by their Fitness to join with, and cover those venomous _Spicula_ that are on float; and to mix with the Animal Fluids by Respiration and Insinuation into the Pores, whereby they convey, as it were, an _Antidote_, wheresoever the Poison is able to penetrate, and which grosser Vapours can by no means do.

OF this kind are chiefly _Storax_, _Benjamin_, _Frankincense_, and all the Aromatick Roots and Woods; and amongst them all, I cannot think the Smell of _Tar_, _Pitch_, &c. is inferior in any Respects, where its Scent is not particularly offensive. And these Things should be burnt at such Distances of Time from each other, that the Air may be always sensibly impregnated with them.