fected Bales of Goods in the _Lazaretto_'s of
_Marseilles_, died upon the first Appearance of Infection, as it were by
a sudden Stroke; being seized with Rigors, Tremblings, Heart-Sickness,
Vomitings, Giddiness and Heaviness of the Head, an universal Languor and
Inquietude; the Pulse low and unequal: and Death insued sometimes in a
few Hours.

EFFECTS so sudden must be owing to the Action of some Corpuscles of
great Force insinuated into, and changing the Properties of, another
subtle and active Fluid in the Body: and such an one, no doubt, is the
_Nervous Liquor_.

IT is not to be expected that we should be able to explain the
particular manner by which this is brought about. We know too little of
the Frame of the Universe, and of the Laws of _Attractions_,
_Repulsions_ and _Cohesions_ among the minutest Parcels of Matter, to be
able to determine all the Ways by which they affect one another,
especially within animal Bodies, the most delicate and complicated of
all the known Works of Nature. But we may perhaps make a probable
Conjecture upon the Matter. Our great Philosopher, whose surprising
Discoveries have exceeded the utmost Expectations of the most
penetrating Minds, has demonstrated that there is diffused through the
Universe a _subtile_ and _elastic Fluid_ of great Force and Activity.
This he supposes to be the Cause of the _Refraction_ and _Reflection_ of
the Rays of Light; and that by its _Vibrations_ Light communicates Heat
to Bodies: and, moreover, that this readily pervading all Bodies,
produces many of their Effects upon one another[50].

NOW it is not improbable that the _Animal Spirits_ are a thin Liquor,
separated in the Brain, and from thence derived into the Nerves, of such
a Nature that it admits, and has incorporated with it, a great Quantity
of this _elastic Fluid_: which makes it a vital Substance of great
Energy. And a Liquor of this kind must be very susceptible of
Alterations from other active Bodies of a different Nature from it, if
they approach to and are mixed with it: as we see some _Chemical
Spirits_ upon their being put together, fall into a Fermentation, and
make a Composition of a quite different kind.

IF therefore we allow the _Effluvia_ or _Exhalations_ from a corrupted
Mass of Humours in a Body that has the _Plague_ to be volatile and firey
Particles, carrying with them the Qualities, of those fermenting Juices
from which they proceed; it will not be hard to conceive how these