d by _Infection_, ascribe the Rise
of it wholly to the malignant Quality of the _Air_ in all Places,
wherever it happens; and, on the other hand, some have thought that the
Consideration of the infectious Nature of the Disease must exclude all
regard to the Influence of the _Air_: Whereas the _Contagion_
accompanying the Disease, and the Disposition of the _Air_ to promote
that _Contagion_, ought equally to be considered; both being necessary
to give the Distemper full force. The Design therefore of this Chapter,
is to make a proper Balance between these two, and to set just Limits to
the Effects of each.

FOR this purpose, I shall reduce the Causes, which spread the _Plague_,
to three, _Diseased Persons_, _Goods transported from infected Places_,
and _a corrupted State of Air_.

THERE are several Diseases, which will be communicated from the Sick to
others: and this not done after the same manner in all. The
_Hydrophobia_ is communicated no other way than by mixing the morbid
Juices of the diseased Animal immediately with the Blood of the sound,
by a _Bite_, or what is analogous thereto; the _Itch_ is given by
_simple Contact_; the _Lues Venerea_ not without _a closer Contact_; but
the _Measles_, _Small-Pox_, and _Plague_ are caught by a _near Approach_
only to the Sick: for in these three last Diseases Persons are render'd
obnoxious to them only by residing in the same House, and conversing
with the Sick.

NOW it appears by the Experiments mentioned in the _Preface_, of giving
the _Plague_ to _Dogs_ by putting the _Bile_, _Blood_ or _Urine_ from
infected Persons, into their Veins, that the whole mass of the animal
Fluids in this Disease is highly corrupted and putrefied. It is
therefore easy to conceive how the _Effluvia_ or Fumes from Liquors so
affected may taint the ambient Air. And this will more especially
happen, when the Humours are in the greatest Fermentation, that is, at
the Highth of the Fever: as it is observed that fermenting Liquors do at
the latter end of their intestine Motion throw off a great Quantity of
their most subtile and active Particles. And this Discharge will be
chiefly made upon those Glands of the Body, in which the Secretions are
the most copious, and the most easily increased: such are those of the
Mouth and Skin. From these therefore the Air will be impregnated with
_pestiferous Atoms_: which being taken into the Body of a sound Person
will, in the Nature of a _Ferment_, put the Flui