A 
TREATISE 
OF
FEAVERS, 
In which is Contain'd, 
A DESCRIPTION 
Of the Nature of 
Fermentation; 
TOGETHER, 
With the Causes, Symptoms, 
and Cures of all 
FEAVERS. 
Written Originally in Latin, by the 
Author of Riverius Reformatus. 
London Printed, and Sold by E. Bald- 
win, at the Oxford-Arms in War- 
wick-Lane, 1701.



THE 
Translator’s 
PREFACE 
TO THE 
READER. 
THE Author of this Trea- 
tise having Collected into 
one Volume an accurate and ex- 
act Description of all the Disea- 
ses incident to Humane Bodies, 
has thought fit to imitate Rive- 
rius’s method of Practice as near 
as possibly he could, and there- 
fore gave to his Book the Title 
A2 of


The Translator’s 
of Riverius Reformatus; but 
in the theoretical enquiry into 
the Causes of Distempers fol- 
lows the Modern Hypotheses, 
which our late Discoveries of 
Anatomy and Chymistry have 
introduc’d: For tho’ the Anci- 
ents were very Diligent and 
Faithful in observing all the 
various Symptoms and Periods 
of Diseases, and tho’ their Ex- 
perience and Success in Curing 
the same were so Remarkable, 
that their Writings to this 
Day do serve for a Model and 
Standard of our Modern Pra- 
ctice; yet their Ignorance of 
the Circulation of the Blood, 
and several other things rela-
ting 

Preface to the Reader. 
ting to the Oeconomia Ani- 
malis, occasion’d many mistakes 
in explaining the Causes of 
Diseases; which our Author 
has effectually amended, in 
Chaining together the Discove- 
ries of the later, and Experi- 
ence of former Ages; presenting 
us at one view both with the 
Improvements that of late Years 
have been made in Physick, 
and with the applauded Methods 
of Cure that are built upon the 
Experiences and Observations 
of the Ancients: So that the 
Modern Suppositions he lays 
down are so far from overturn- 
ing the Ancient Practice, that 
they serve rather to unfold the
reasons

The Translator’s 
reasons of the Phænomena, 
Symptoms, and Cures, observ’d 
and perform’d by them, with- 
out any other Guide but blind 
Experience. 
This small Treatise of Fea- 
vers makes in Bulk but an in- 
considerable part of the Book; 
but for its fulness, accuracy, 
and conciseness may vie with any 
of its Fellow-companions; for 
so much as it contains in so 
few Pages all the Doctrine of 
Fermentation in General (which 
Willis and several other Au- 
thors have spent so many Chap- 
ters upon; and which is a ne- 
cessary Antecedent to the De- 
scription of Feavers, since they
all

Preface to the Reader. 
all depend upon, nay rather con- 
sist in, a Fermentation) and an 
accurate enquiry into the Causes 
of Feavers, of which so many 
Hypotheses have been form’d; 
together with a Circumstantiat 
Account of the Symptoms, Signs, 
Periods, and Degrees of the 
same; All which is follow’d by 
the Indications of Cure, which 
are plainly and rationally de- 
duc’d and inferr’d from the Hy- 
pothesis which is here advanc’d. 
The Forms of Prescription, our 
Author has thought fit to omit, 
by reason that they are so com- 
mon and to be met with every 
where; and that the only dif- 
ficulty or business of a Physician
con-

The Translator’s Preface. 
consists in a distinct Per- 
ception of the general Indicati- 
ons. 
To Conclude, The Entertain- 
ment that this and all the other 
Writings of our Learned and 
Ingenious Author have found 
beyond Sea, do encourage me to 
hope that it shall meet with the 
like Reception from our English 
World.
A 

(1)
A 
TREATISE 
OF 
FEAVERS. 
SEEING that all Feavers, of 
what Nature soever, are ac- 
company’d with a Fermen- 
tation in the Mass of the Blood; 
and that the Physicians of this pre- 
sent Age have Exploded that An- 
tiquated Notion of a Feaver’s be- 
ing a preternatural heat kindled 
in the Heart, and from thence di- 
stributed through the Arteries to 
all the parts of the Body; and in 
Leiu of the same, have embrac’d 
the Opinion of its being a Fermen-
B tative 

(2)
tative and Intestine Motion of the 
parts of the Blood: I thought it 
not Improper, before I commence 
the Description of the Natures, 
Differences, and Causes of Feavers, 
to premise somewhat of Fer- 
mentation in General; which, if 
rightly understood, shall contribute 
not a little to the clearer under- 
standing of this Treatise. The 
word Fermentation then is deriv’d 
from the Ferment, which, for the 
most part, causes or rather occasi- 
only gives Rise to this Motion; 
or from the Effervency and Heat 
which is most frequently observ’d 
in Fermented Bodies. Of old it 
was only attributed to such com- 
pound Bodies, as by the Addition 
and Commixtion of a Ferment, or 
the like, did swell and puff up, and 
thus beget an Intrinsecal Motion in 
their inward parts, as it happens 
in Paste or Dough, in Beer and 
Spirituous Juices, whether of the
Vine 

(3)
Vine, or others that by Distillation 
yield hot and ardent Spirits; which 
of their own accord, without the 
Intervening of any Extrinsick Bo- 
dy, use to rise up, and undergo a 
Motion of their parts, such as Must, 
Syder and other Liquors express’d 
from Fruits and Spirituous Plants. 
But now its signification is become 
more universal, extending it self 
not only to Dough, Must, Ale, Beer, 
and such like, but to several other 
things; insomuch that amongst our 
modern Phisicians there is no Moti- 
on at least of humid Bodies in all the 
threefold Regnum, whether Mine- 
ral, Vegetable or Animal, that is 
not entitl’d a Fermentation; all 
which I cannot but approve of, 
by reason of that Similitude and 
Analogy which the intestine Mo- 
tion of the Humours and Juices, 
lock’d up in Plants, Animals, and 
the Bowels of the Earth, bears to 
the Fermentation of Paste, Must, and 
Beer.
B2 But 

(4)
But that I may confine my Dis- 
course to the Motion of the Blood, 
and other Humours contain’d in 
Humane Bodies; that, being a 
more proper Subject for our pre- 
sent purpose; I hope no Man in his 
right Wits will have the Impudence 
to deny, that the Natural Heat 
which Man, and all other Living 
Creatures, are equally Possess’d of, 
do’s depend upon the Circulating, 
but more especially the Fermenta- 
tive, Motion of the Blood; with- 
out which the Constituent Ele- 
ments of Blood, being Heterogene- 
ous and of different Natures, would 
unlock the bonds of their Mixtute, 
separating mutually from one ano- 
ther, as we see they do in Blood 
let forth from the Veins. And in- 
deed, being that many Philosophers 
have justly determin’d the Nature 
of Heat, to consist in the Motion 
of the Particles contain’d in its 
Subject; and that all Fermented
Bodies, 


(5)
Bodies, especially such as are co- 
piously Impregnated with Spirit, 
Oil, or Sulphur, are in a continual 
Heat; it is highly reasonable that 
the Blood of Animals, which is 
always Hor, and receives Augmen- 
tation of Heat in proportion to 
the encrease of its intestine Motion, 
should owe the Original of this its 
Natural Heat to no other cause, 
than that of the Mutual Strife and 
Justling, or Fermentation of its Ele- 
mentary Particles. For as there 
be in Dough, Must and Beer, se- 
veral Heterogeneous and Dispropor- 
tionate Particles, which dispose ’em 
for Fermentation; in like manner 
the Chymical Resolution of the 
Blood discovers to us several Ele- 
mentary Principles, which are Spi- 
rit, Salt, Sulphur, Water, and Earth; 
whose different and disagreeable Fi- 
gures are apt to produce the like 
Effect in it. 
B3 But

(6)
But to prevent all Obscurity, be- 
fore I proceed further, I shall here 
explain the Nature of Fermenta- 
tion, which may be defin’d to be 
An Intestine and Expansive Motion 
of the Heterogeneous and Dispropor- 
tionate Parts of a Humid Body, in 
a free and unconfined Space, without 
the accession of any external Sen- 
sible Cause, producing either a total 
or partial Change and Alteration of 
the Fermented Body. This Defini- 
tion seems to me, to be as accu- 
rate and exact as any can be given, 
as I shall make to appear by a 
circumstantiate and particular Ex- 
plication of every word contain’d 
in the same: And first of all, I 
define it to be, An Intestine and 
Expansive Motion: The Motion is 
Obvious to our Senses in several 
Fermented Bodies, such as Dough, 
new Wine, &c. Sometimes indeed 
when the Fermentation is weak and 
fainter, the motion is not so sensi-
ble 

(7) 
ble, but may be easily gather’d and 
inferr’d from the change of Co- 
lour, and other alterations procur’d 
in the Subject; and in this it a- 
grees with all other Motions that 
are not Fermentative, such as the 
moving of Water, Wine, &c. by 
the external force of the Hand; 
or the motion of running Waters, 
and the like. This Motion is said 
to be Intestine and Expansive, be- 
cause it is produc’d in the Centre 
or Bowels of its Subject, from 
whence the Intrinsick Particles seem 
to move and stretch themselves to- 
wards the Circumference, causing 
it to swell, and become turgid; 
which quality is not to be found 
in the other Motions of Humid 
Bodies. In the next place it is 
said to be a Motion of the Hetero- 
geneous and disproportionate Parts; 
giving us to understand that all 
manner of Heterogeneity and Dif- 
ferent Figuration of parts is not
B4 neces- 

(8)
necessary for Fermentation, only 
such as is accompanied with a great 
Irregularity and Disproportion a- 
mong its parts; or (as I shall 
have occasion to observe anon) 
such a Constitution of parts as af- 
fords and easie and dis-encumber’d 
entrance to the subtil ethereal mat- 
ter, but a difficult and uneasy Re- 
treat. For were it not so, all sorts 
of Liquors, whose parts being of 
different Magnitudes and Forms, 
are Essentially in Motion, might 
justly Challenge to themselves the 
Title of Fermentation, which all 
the World must own to be absurd. 
Hence ’tis that such Bodies as 
are endu’d with a similitude and 
uniformity of parts (that is, such 
particles as in their shapes and forms 
do mutually resemble and agree 
with one another ) do continue 
quiet and undisturb’d in the same 
lasting State and Condition; where- 
as were a Disproportion advanc’d by
adding 

(9)
adding particles of different Natures, 
as for example, Spirit of Wine to Spi- 
rit of Turpentine; or Oyl of Vitriol 
to Oyl of Tartar, presently there 
arises an Effervescency and Fermen- 
tation, introducing several altera- 
tions. ’Tis added moreover, of a 
Humid Body, by reason that Fer- 
mentation properly belongs to Hu- 
mid Bodies, or at least to such as 
in some measure participate of Hu- 
midity or moistness; for tho’ Lea- 
ven of Bread, Triacle, and such 
like things of a thicker consistency, 
seem to possess but a small share of 
Humidity; yet they are not so 
dry or compact as not to retain so 
much moistness as makes ’em soft 
and pliable; upon the account of 
which they are justly said to be 
Fermented, or to swell and heave 
up by virtue of an Intrinsick Moti- 
on in their inward parts. From 
whence we infer that dry, hard, 
and compacted Bodies are not qua-
B5 lified

(10)
lified for undergoing a Fermenta- 
tion; which is likewise attested by 
Experience it self, for their parts 
being strictly united one to another 
in a quiet and restful Peace, are 
free from those Strifes and Jarrs that 
in moist and softer Bodies, (where 
the System of the Parts, is loose and 
disengaged) provoke one another 
to mutual and reciprocal Motions. 
The words that come next in or- 
der, are, in a free and unconfined 
Space, by reason that ’tis impos- 
sible a Fermentative Motion should 
succeed without sufficient Place and 
room left for the swelling and ri- 
sing up of the Fermented Body; 
for where a Body is rarified (as all 
Fermented Bodies are) and gives en- 
trance and admission to new mat- 
ter from without; there must need- 
fully ensue an encrease of exten- 
sion, which consequently requires 
a larger and more capacious space. 
And ’tis by Vertue of this deficiency
of

(11)
of place that Casks, when filled with 
Newprest wine or Must, stopp’d 
close, do burst asunder; or that 
Earthen and Glass Vessels are bro- 
ken into pieces, when the Liquors 
too plentifully contain’d in ’em, are 
assaulted by a Violent Boyling and 
Fermentation; nay, and to the 
same very cause is owing the 
breaking of the Blood Vessels in 
Plethorick Feavers. But if the walls 
and sides of the Vessels containing 
such Liquors, be so strong as to 
surmount the shock of the Fermen- 
ted Liquors, then the Fermentation 
becomes very weak and slow-pac’d; 
nay, scarce any at all. Next fol- 
lows, Without the accession of any 
external Sensible Cause; which 
words distinguish a Fermentative 
Motion from that of Burning and 
Boyling; for Boyling Water and 
Burn’d Wood are not properly 
said to be Fermented, nor yet such 
Liquors as are agitated and mov’d
by

(12)
by the Gales of the Circumambient 
Air; because that all such Motions 
are owing to sensible Causes, the 
Fire, Air, &c. whose external im- 
pulses give rise to the different Agi- 
tations and Commotions of these 
Bodies. The last words of the De- 
finition (which are, Producing ei- 
ther a total or partial Change and Al- 
teration of the Fermented Body) 
serve to signifie that the end of 
Fermentation consists in changing 
the Fermented Body, into some- 
thing different from what it was 
before: And this change is either 
total and perfect as in Generation 
and Corruption of Bodies, where all 
the parts receive from Fermenta- 
tion a new Situation or Order, and 
new Shapes or Figures; insomuch 
that the whole compound seems to 
be moulded afresh, and cloathed 
with a new Form: or only partial 
and imperfect, as when the Fer- 
mentative Motion do’s not so much
confuse

(13)
confuse and disorder the Particles, 
or rob ’em wholly of their for- 
mer Shapes, but leaves to the Bo- 
dy somewhat of its Ancient Form, 
and Superficial Appearance; in 
which Sense Bodies are said to be 
Altered, not Generated or Corrupt- 
ed. 
Having thus explain’d the Na- 
ture of Fermentation, our next task 
shall be to pry into its different 
Kinds. And first of all, with re- 
spect to the different degrees of the 
Fermentative Motion, it is divided 
into Effervescency, and a Fermenta- 
tion properly so call’d. Efferves- 
cency is when the Particles of the 
Fermented Body are so rapidly 
mov’d and toss’d to and again, 
that their Tumultuous Agitation is 
both heard by the Ears, and visi- 
ble to the Eyes; when like boyling 
Water they rise and swell up, 
throwing out Fumes and Vapours; 
and for the most part are hot to a 
high

(14)
high and intense degree. Chymistry 
furnishes an infinity of Examples 
of this Nature, whether in the mix- 
ture of contrary and opposite Li- 
quors or Spirits; as Spirit of Vi- 
triol with Oil of Tartar; and Spirit 
of Turpentine with Spirit of Wine, 
in a word, an Acidum with an 
Alkali; or in the Dissolutions 
of Stones and Metals; which, 
being hard and solid, cannot be 
Fermented of themselves, as was 
remark’d but now; but when an 
acid or corrosive Liquor is pour’d 
upon ’em, the disproportion and 
disagreement of the surface of the 
Stone or Metal with the Particles 
of the Liquor immediately grating 
upon it, causes such a forcible and 
impetuous concussion, as pulls asun- 
der and separates the parts of the 
solid Body one from another, till 
at length the whole be divided 
and dissolv’d into such minute 
small Particles as can hide them-
selves 

(15)
selves without Disturbance in the 
pores of the Dissolving Liquor; 
and thus being agreeably Propor- 
tionated one to another, they make 
an end of their Strife and Efferves- 
cency. The other Species of Fer- 
mentation, which is opposite to 
Effervescency, retains the Name 
of its Genus, and is said to be such 
when the Motion and Agitation of 
the Particles of the Fermented Bo- 
dy is more moderate; when the 
Fumes and Steams are not exhal’d 
so copiously, and the whole obtains 
a remisser degree of Heat; as is ex- 
emplified in Paste, Must, new Beer, 
and all other Bodies that Ferment 
after a meek and gentle manner. 
In like manner, as to the Sub- 
jects in which Fermentation is rais’d, 
it is divided into Natural and Ar- 
tificial: The Natural is a Fermenta- 
tion in which the help of Artifi- 
cers or the assistance of Art is not 
at all requir’d or made use of;
but 

(16)
but the whole work is absolved by 
Nature it self; such as we see in 
the Juices of Vegetables, and the 
Principles of Minerals lock’d up 
in the Bowels of the Earth; and 
in the Blood and other Humours 
of Animals, which needfully un- 
dergo a Fermentation for perform- 
ing the Animal Functions of Nou- 
rishment, Generation, mantaining 
the Natural Heat, &c. The Arti- 
ficial is such as is procur’d by the 
Preparation of Art, especially by 
mingling different Bodies together, 
and applying actives to passives, 
after the manner of the Chymical 
Preparations and Experiments. 
The Natural Fermentation is sub- 
divided into that which is perfective, 
when the Fermented Body is Meli- 
orated and Perfited by the Fermen- 
tation; and that which is Corrup- 
tive, when it decays and suffers by 
Fermentation. But indeed, seeing 
that the Generation of one thing
is 


(17)
is the Corruption of another, this 
Division cannot be of any great 
moment. Which is likewise to be 
said of all the other accidental Di- 
visions taken from the length or 
shortness of its duration, or the 
difference of its subject, whether 
Mineral, Vegetable or Animal. 
As to the causes of Fermentation, 
we meet with many different Opi- 
nions of the many Authors that have 
wrote upon that head. Some think 
the Fermentative Motion is rais’d 
from within (without the accession 
of any extrinsecal cause) by the 
agility and nimbleness of the Spi- 
rits, which being the more subtil 
and active Principle of the Body, 
endeavour to disengage themselves 
and fly away; which can never be 
attempted without the agitation 
and commotion of the thicker and 
grosser parts, in which they are 
entangled; and this stir or tumult, 
say they, receives Augmentation
or 

(18)
or decrease in Proportion to the 
greater or lesser Numbers of Spi- 
rits that occasion it. Those who 
hold Water, Air, Earth, and Fire 
to be the Elements or first Princi- 
ples of Bodies, affirm the Particles 
of the Fire that lie hid in every 
compound Body to be the cause of 
Fermentation; so that they reason 
of the Fire, and its Operations 
much after the same manner, that 
the Chymists do of their Spirits; 
many of ’em imagine that those 
Bodies we call Alkalies, which are 
reverberated with Fire and Heat, 
contain an infinite number of fiery 
Corpuscules imprisoned within 
their Pores, that upon the least 
occasion of Releasement spring out 
with an impetuous force, by ver- 
tue of their volatile and active Na- 
ture. Hence, say they, Water 
pour’d upon Limestone, makes a 
tumultuous Motion, and Liquors 
pour’d upon Calcinated Metals or 
Stones,

(19)
Stones, raise a visible Fermentation. 
Others alledge, that the Fermen- 
tative Motion is caus’d by the re- 
ciprocal action and strife of an Al- 
kali and an Acid; both which, they 
say, are to be found in all Bodies. 
They took occasion to frame this 
Hypothesis from the Artificial Ef- 
fervescencies which the Chymists 
present ’em with, by mixing an 
Acid with an Alkali. They de- 
fine an Acid to be a Body endowed 
with long pointed Particles, such 
as grate strongly upon the Organ 
of Taste, and sink deepest into its 
Pores, as the Juice of Limons, Spi- 
rit of Vitriol, Wine, &c. But an Al- 
kali, say they, is a Body which be- 
ing Calcinated by Fire or Heat, 
becomes all over porose and spungy, 
by the passing and repassing of 
these fiery Corpuscules through its 
substance, and thus is fitted for 
absorbing or sucking up the sharp- 
pointed Particles of the Acid, and 
lodging

(20)
lodging them within its own pores; 
but this cannot be perform’d with- 
out a Fermentation or Tumult in 
its parts, which, according to them, 
proceeds from the penetrative qua- 
lity of the Acid that drives in its 
pointed Particles, like so many 
wedges, into the substance of the Al- 
kaline Body, endeavouring to cleave 
and separate its parts one from ano- 
ther, till at length in the progress 
of time either the Alkali be totally 
dissolv’d, or the Acid by being entan- 
gl’d and imprison’d within its Pores 
be obliged to surcease the motion. 
But there is yet another Sect of 
Philosophising Wits, that enquire 
into the matter more narrowly, 
examining it by the Rules of 
Philosophy more than those of 
sense, whose opinion in this case I 
cannot but embrace and approve 
of. They are of opinion that 
the motion of fermented Bodies, 
tho’ it seem to be raised from with- 
in;


(21)
in; that is, by their constituent 
Parts; yet it is in it self truly ad- 
ventitious, or is first of all excited 
by an External Cause, which is no 
other than what passes among the 
modern Philosophers, by the name 
of the subtil and ethereal matter; 
the existence of which is sufficient- 
ly demonstrable both by reason 
and experiment; and upon which 
God, the first Author of all Mo- 
tion, hath confer’d, as an essential 
property, an extream swiftness and 
rapidity of motion, by Virtue 
whereof it penetrates and fills the 
Pores of all Bodies, and thus may 
justly be accounted the only cause 
of all sublunary motion, and by 
consequence of Fermentation, which 
it causes so often as any Body that 
affords to it an open and patent 
access into its Pores, denies it the 
like freedom or case of retiring and 
disengaging it self of the same; 
for then having the advantage of a 
wonder-

(22)
wonderful mobility as well as smal- 
ness of parts, it breaks through 
the gross resisting parts that ob- 
struct its passage, and forces ’em 
back on all sides, from whence 
ensues a turgescency and swelling 
up, which is observ’d to augment 
or decrease, in proportion to the 
greater or lesser numbers of ethereal 
particles that have crouded in, or 
to the greater or lesser resistance 
made by the grosser parts; but 
continues still, till such time as the 
ethereal matter have clear’d its way 
on all hands, and traced out a free 
passage for sallying out and in; 
upon which it surceases all agita- 
tion or division of the grosser parts, 
leaving ’em an undisturb’d Peace 
and Quiet, such as we see, not 
only in Bodies that never were 
Fermented, but even in those that 
have undergone the most strong 
and tumultuous Effervescency.
The 

(23)
The Occasional Cause that pre- 
pares and disposes the fermented 
Bodies for a free reception and ad- 
mission of a large and unusual quan- 
tity of ethereal matter, is that He- 
terogeneous Irregularity and Dis- 
proportion of parts, mention’d a- 
bove; which hinders a close and 
fit application or joyning of the 
parts one to another; so that large 
chinks and passages are left for the 
ingress of the ethereal matter, which 
upon such an occasion throngs 
in very copiously. Hence it is, 
that all Ferments do raise a Fer- 
mentation in the Bodies they are 
mixed with, only by the dispro- 
portion’d figure and shape of their 
own Particles to those of the fer- 
mented Body; and that Chymical 
Liquors, when mix’d together, do 
not ferment unless their Particles 
be of contrary and different forms, 
as in Acids and Alkalies which 
ferment and efferversce, only be- 
cause


(24)
cause the constituent Particles of 
the one are not of such an agree- 
able Configuration as to cohere and 
cement with those of the other, 
without mutual Strifes and Jarrs. 
In fine, where-ever there is a suf- 
ficient Heterogeneity and Dispro- 
portion of the Parts, there neces- 
sarily ensues a turgescency or swel- 
ling upon the account, and in the 
manner already mention’d. For 
which cause it is, that in all Fer- 
mentations of the Blood we always 
accuse its Heterogeneous parts. 
This last Hypothesis which at- 
tributes the whole work of Fer- 
mentation to the ethereal matter, 
as being the first, chief and efficient 
cause of the same, is most univer- 
sally received amongst the wiser 
sort of Physicians, and seems indeed 
to be preferable to any that has 
been yet advanc’d; for ’tis impos- 
sible that any Body whatsoever, 
tho’ impregnated with Spirit and
fiery 

(25)
fiery Particles, or tho’ enfolding in 
its Womb the struggling twins of 
an Alkali and an Acid, can ever 
acquire or produce a greater moti- 
on than it has in it self; whether 
it be of its own accord, or by the 
addition of a ferment, or the ap- 
plication of actives to passives; since 
’tis the constant and immutable 
Law of Nature, that all Bodies do 
persevere in the same state in 
which they are plac’d, unless justl’d 
out of it by some external agent: 
How is it possible then that a Fer- 
ment, which has no sensible moti- 
on in it, when added to Bread, 
Beer, and such like, that are as 
void of motion as it self, should 
cause such a stir and agitation, and 
produce such an intense heat, as 
they both partake of, when mu- 
tually fermented together? Or how 
can the Spirit of Vitriol, added to 
the Oil of Tartar, or Water pour’d 
upon Limestone, create such a tu-
C multuous 


(26)
multuous Effervescency; since they 
are all known Strangers to any 
sensible motion in their separate 
States? Why should an Acid en- 
gag’d with an Alkaline Body, move 
more strongly than it did before; 
or the Particles of Fire emprison’d 
in the Pores of calcinated Alkalies, 
and therefore in little or no agita- 
tion, stir up themselves all of a sud- 
den, and perform such violent acti- 
ons? Or how can the Spirits that 
but now were entangled and dis- 
possessed of their mobility, upon 
the approach of a Fermentation, 
disengage themselves, and put on 
their ancient mobility? That Law 
of motion I mentioned but now, 
which is receiv’d and acknow- 
ledg’d by all Philosophers, puts it 
beyond all peradventure, that no 
colour of solution can be given to 
the difficulties here advanc’d, with- 
out the allegation of some very 
light and mobile matter arriving 
from

(27)
from without, such as the ethereal 
matter, or the matter of the first 
Element, which throngs into their 
pores, in greater or lesser quantity, 
as the disposition and configuration 
of their parts and pores is more 
or less open and gaping; and ha- 
ving thus penetrated into, and di- 
vided their grosser parts, it tosses 
’em up and down, sometimes very 
tumultuously, at other times but 
gently and with a meeker force. 
In the mean while ’tis to be re- 
mark’d, that tho’ we assert the 
ethereal matter to be the chief and 
principal cause or Fermentative mo- 
tions, yet we do not exclude seve- 
ral other asisting causes, such as 
the Elastick parts of the Air, which 
enter the pores of the fermented 
Bodies, (they being already dilated 
by the ingress and motion of the 
ethereal particles) and contribute 
not a little to the division and se- 
paration of the grosser parts, by
C2 blowing 


(28)
blowing and puffing ’em up, till 
they rise in Bubbles, as Experience 
confirms. In like manner, the sub- 
til and active Particles or Spirits of 
the fermenting Bodies, receive an 
encrease of motion from the ethe- 
real matter (which is much more 
mobile than they) and thus do 
assist and succour the same 
in compassing its end. But I 
have already insinuated, that the 
effect or end of Fermentation is, 
that through the various agitations, 
separation and attenuation of the 
fermenting Body, its parts may ob- 
tain an uniform and proportionable 
nature, so that the subtil mat- 
ter may have a free egress and 
regress on all sides; or that the 
gross resisting parts may be re- 
mov’d out of the way, either by 
Precipitation to the bottom, or by 
enlarging the Circumference of the 
fermented Body through an expan- 
sive motion, or by casting ’em
quite

(29)
quite out of doors, if any patent 
way be found. The verity of all 
which is evident from that one 
instance of Must or New Wine. 
’Tis likewise to be here remark’d, 
that in establishing the subtil mat- 
ter for the cause of Fermentation, 
we deny not the efficacy of an 
Acid and Alkali mix‘d together in 
advancing the same; for that we 
plainly see, by the Experiments of 
Chymistry, that where-ever they 
meet or rencounter one another, 
they forthwith become turgid, and 
ferment. But before I proceed to 
explain wherein this Efficacy con- 
sists, or how that turgescency en- 
sues upon applying the one to the 
other, I think it not amiss to adver- 
tise my Reader, that the names of 
Acid and Alkali do not signifie an 
absolute but a relative Quality. 
For there could be no Fermenta- 
tion rais’d betwixt the Acids and 
Alkalies of several kinds, if they
C3 were

(30)
were absolutely such; for in that 
case there would be no Alkali at 
all. And in like manner no turges- 
cent or swelling motion could fol- 
low upon the mixture of two or 
several Liquors, if neither of ’em, 
be absolutely Acid, such as Spirit 
of Turpentine, Wine, Urine, &c. 
All which is evidently false; for 
Experience attests that there be se- 
veral Acid Liquors, Heterogeneous 
and Disproportion’d to one ano- 
ther, which ferment upon a mutu- 
al approach; and likewise that 
there be several sulphureous and 
sharp Liquors that ferment with 
one another: Nay moreover, that 
there be many other Bodies in 
which the taste cannot discern any 
thing, either of an Acid or an Al- 
kali, that ferment when mix’d to- 
gether, as ye may read in De Gra- 
ef's Writings. All which do’s 
sufficiently argue, that Acids and 
Alkalies are not said to be such
abso- 

(31)
absolutely in themselves, but with 
respect to the Bodies with which 
they use to ferment. Thus Water, 
which is not Acid in it self, may 
be said to be relatively such in re- 
spect of Limestone, and other cal- 
cinated Bodies; and Spirit of Wine 
may be named an Acid in respect 
of Spirit of Urine, for as much as 
it performs the Office of an Acid. 
And in like manner among the 
Acid Liquors, which ferment with 
one another, one of ’em may be 
said to be an Alkali, for as much 
as it supplies the place of an Alkali; 
For all Bodies whatsoever that fer- 
ment with one another, tho’ in 
taste they discover nothing resem- 
bling an Acid and Alkali; yet in 
the mixture, situation, order and 
configuration of their Parts and 
Pores, have such a mutual relation 
and disproportion to one another, 
as is seen betwixt the real Acids 
and Alkalies, such as the Spirit of
C4 Vitriol 


(32)
Vitriol and Oil of Tartar, mix’d to- 
gether; so that ’tis nothing won- 
derful or extraordinary if such Bo- 
dies be said to effervesce, and fer- 
ment, after the same manner that 
Acids and Alkalies use to do. In 
Fine, all Effervescencies and Fer- 
mentations are solely owing to the 
Disproportion and Heterogeneity 
of the parts, as I have said already; 
and hence we conclude, that as 
Acids and Alkalies, when mix’d 
and confus’d, are visibly seen and 
acknowledg’d to ferment; so all 
other Bodies, of what nature so- 
ever, if accompany’d with such a 
Heterogeneous and Irregular Dis- 
position of parts as may make way 
for the tumultuous ingress of the 
ethereal matter, are justly said to 
undergo the like Fermentation. 
And by this we are led to under- 
stand the various disposition of di- 
vers Alkalies and Acids for their 
relative Fermentations; for though
they 


(33)
they all agree in general in being 
either Acids or Alkalies, yet they 
differ from one another in the par- 
ticular conformation of their parts; 
as for example, there be Acids of 
several sorts, tho’ all endou’d with 
pointed and sharp particles; some 
have Cylindrical, others Triangu- 
lar, Quadrangular, or Pyramidal 
Parts; some are more or less point- 
ed than others; some in the Form 
of a Needle, others in the Form of 
Spear; whence slow the different 
natures and actions of Spirit of Vi- 
triol, Nitre, Sulphur, Salt, Aqua 
Regalis, destill’d Vinegar, Juice of 
Limons, Berberis, &c. All which 
agree in being Acid, but produce 
different Effects with respect to the 
different Configuration of the parts. 
Hence some of these Liquors dis- 
solve Silver, some Iron, some Cop- 
per; others Gold; some Ferment 
with some peculiar Bodies, tho’ 
not with all of an Alkaline nature;
C5 some 

(34)
some dissolve Lead, others cannot; 
some precipitate Bodies dissolv’d 
in salt or sharp Liquors, which o- 
thers refuse to do; and some dis- 
folve Stones, Earths, and Shells: 
The variety of all which operati- 
ons is only owing to the difference 
of the pores of the Fermented or 
dissolved Bodies, which the Acids 
diversified in the configuration of 
their parts are not all equally dis- 
posed to reach and penetrate. 
What I have said of Acids is e- 
qually applicable to Alkalies, which 
are divided into several different 
kinds; for some are quite dry, as 
the calcinated Alkalies, Stones, 
Shells, Earths, Metals, Corals, 
Pearls, fix’d and volatile Salts, &c. 
others are moist, and to speak pro- 
perly are nothing else but these 
volatile and fix’d Salts dissolv’d in 
a watery Vehicle; as the Oyl of 
Tartar, and such like, that are made 
of fixed Salts per deliquium; the 
Spirit


(35)
Spirit of Wine, Hartshorn, Sal-ar- 
moniack, and such like volatil Spi- 
rits which are meerly a dissolution 
of their volatil Salts. Besides, some 
Alkalies are Salt as all the vola- 
tile and lixivious Salts; others are 
more compounded and immersed 
in heavy matter, such as Stones, 
Earths, Corals, &c. But in the 
mean while we are to remark by 
the bye, that all effervescencies of 
Liquors or compound Bodies do 
not always proceed from an Acid 
or Alkaline Salt lock’d up and em- 
prison’d within their pores (as 
some would have it) but rather 
from their own constituent and in- 
tegral parts, the disproportion and 
irregularity of which is sufficient 
for admitting greater quantities of 
ethereal matter, and thus advancing 
a Fermentation after the manner 
above-mention’d. Moreover, Alka- 
lies are divided into several sorts, 
by the diversity of their Pores; for
as 

(36)
as the nature of Acids consists in 
the length, hardness, and sharpness 
of their parts; so that of an Alka- 
li in the porosity, or abundance of 
pores, which are of different forms, 
sometimes long, at other times 
round, or square, or triangular, or 
hexagonal, &c. whence arise the 
different Species of Alkalies that are 
variously disposed for absorbing 
their respective Acids; that is, such 
as are proportion’d to, and fit to be 
lodg’d within, their pores. 
But while we are discoursing of 
Fermentation ’tis needful to ob- 
serve, that sometimes, tho’ very 
rarely, even strong Fermentations 
are not accompany’d with any heat, 
as in the Fermenting of Corals with 
destill’d Vinegar, where there is no 
heat perceiv’d, tho’ the noise of 
their motion be pretty loud; the 
reason of which seems to be this, 
that in these two Bodies there be 
few or no sulphureous parts, which
are 


(37)
are generally the Authors of heat 
in any Body; for we observe that 
all the Oyly or Sulphureous things 
when Effervescencing are intensly 
hot, whereas those that have a les- 
ser quantity of Sulphur, have re- 
misser degrees of heat. Or if we 
choose rather to resolve the Phœno- 
menon by the Cartesian Philosophy, 
it may be alledg’d that in the Fer- 
mentation or Dissolution of Corals 
in Vinegar, the motion tho’ strong 
enough is not circular or vortical, 
such as is essential to heat. 
Another thing worthy to be ta- 
ken notice of in the Fermentations 
of most part of Juices, Liquors or 
other Bodies; is, that after being 
mixed or confusedly jumbled toge- 
ther, and having endeavour’d a 
Fermentative or Effervescing Mo- 
tion proceeding from the Hetero- 
gencity and Disagreeableness of 
their parts, there sometimes en- 
sues a most strict and close union
of 

(38)
of the parts of the Heterogeneous 
Bodies, without any manner of 
precipitation, as in the affusion of 
Spirit of Vitriol upon Salt of Tar- 
tar; but that which is generated 
of their union or mixture is saltish, 
and is divided into several species 
or kinds from the various exalta- 
tion or mixture of the several Acids 
and Alkalies (which are of as ma- 
ny different sorts themselves.) 
Hence Allum, Vitriol, Nitre, Sal 
Gem, Sea-salt, Salarmoniack, and 
Tartarum Vitrolatum, are all ac- 
counted to be of separate and di- 
stinct classes; Sometimes this Effer- 
vescency do’s not produce that 
strict union of the mixed Bodies, 
but only a hiding or concealing 
the parts of the dissolved Body 
within the pores of the dissolver, 
without any manner of Precipita- 
tion, as in the dissolution of Gold 
in Aqua Regalis, or Mercury in 
Aqua Fortis: And in these or such 
like

(39)
like instances the transparency and 
ciearness of the Liquor is not at all 
impair’d, by reason that the parti- 
cles of the dissolved Body are so 
small and subtil as not to stop the 
passage oF the Luminous Bodies. 
’Tis true that if they were all 
joyn’d and combin’d together, their 
united gravity might be sufficient to 
cause a precipitation; but being di- 
vided into small minute particles, 
and all separated from one another, 
their natural levity bouye them 
up; and besides, not only the mo- 
tion of the Liquor keeping ’em in 
continual agitation, but also its 
sharp and pointed particles that are 
darted into the pores of the metal- 
lick Body do keep ’em aloft, and 
thus prevent precipitation. Some- 
times the Effervescency of Hetero- 
geneous Liquors or Bodies is fol- 
low’d by a precipitation; which, 
tho’ it be not a necessary compani- 
on of all Fermentations, yet never
happens 

(40)
happens, unless either a sensible or 
insensible Fermentation make way 
for it; for the grosser parts of the 
mixed Bodies that cannot be easily 
united with the rest, are either beat 
down by the fermenting motion; 
or by their own weight do sink to 
the bottom; or else the particles 
become grosser and heavier by the 
mixture of contrary Bodies, as Spi- 
rit of Urine with Spirit of Wine, 
which after an intense Effervescen- 
cy coagulate and precipitate after 
the same manner that most other 
Bodies do, when incorporated and 
mix’d together. But besides this 
precipitation which follows upon 
the mixture and Effervescency of 
contrary Liquors or Bodies; there 
is yet another sort, which of 
its own accord would never en- 
sue upon the dissolution or fer- 
mentation of these Bodies, unless 
some new Liquor be pour’d upon 
’em, which causes and gives rise to
the 

(41)
the same; but the Liquor must not 
always be one and the same, for 
’tis to be chang’d or varied with re- 
spect to the diverse dissolving or 
dissolved Bodies: Thus Oyl of Tar- 
tar, or Spirit of Salarmoniack pre- 
cipitates Gold when dissolv’d in 
Aqua Regalis: Sea or Salt Water 
precipitates Mercury dissolv’d in 
Spirit of Nitre. The Oyl of Tar- 
tar precipitates Lead or Corals dis- 
solv’d in destill’d Vinegar; simple 
Water precipitates the Flowers of 
Sulphur, when dissolv’d in Water 
impregnated with the Salt of Tar- 
tar: in fine, as several Bodies require 
particular Menstrua to dissolve ’em, 
so when dissolv’d they require dif- 
ferent and peculiar Liquors or Bo- 
dies, that being pour’d upon, or ad- 
ded to them, should cause their 
precipitation. 
Moreover we ought to remark, 
that some certain Bodies dissolv’d 
in their proper Vehicles may be 
preci-


(42)
precipitated, not only by one pecu- 
liar Liquor, but by some two, three, 
or four, more; which, tho’ they be 
not absolutely, and in all respects 
alike, yet they agree in an equal 
proportion and aptitude of parts for 
performing that Office. 
’Tis likewise worth our observa- 
tion, that Bodies dissolv’d by Alka- 
lies are for the most part precipitated 
by Acids; and è contra. But how, 
or by what Mechanism the pouring 
of certain Liquors upon certain dis- 
solv’d Bodies should procure a pre- 
cipitation, is not unanimously de- 
termin’d. Some thinking that the 
Liquor adds new weight to the dis- 
solved Body, by reason of which it 
must needs sink downwards; o- 
thers, that the force of the affused 
Liquor disengages the Particles of 
the dissolv’d Body, which were kept 
aloft by the sharp parts of the dis- 
solver or menstruum fasten’d in 
their pores, but very supeficially,
and

(43)
and thus easily separable; which 
hypothesis they confirm by the ex- 
ample of Acids, that for the most 
part dissolve Metals and solid Bo- 
dies; whose sharp and pointed Par- 
ticles are but slightly and superfici- 
ally fasten’d upon the small pieces 
of the dissolv‘d Mettal, and thus 
detain ’em hovering in its own Bo- 
som, till by the affusion of a new 
Liquor they fall to the bottom; 
that is, till the union of the dissol- 
ver and dissolved be interrupted by 
the force of the Liquor rushing in 
betwixt ’em, and blunting or ra- 
ther breaking off the sharp extre- 
mities of the Acid Particles that 
had fasten’d themselves in the pores 
of the Mettal: Hence they alledge 
a reason why all the precipitated 
Bodies, especially those that are dis- 
solv’d in Acids, do still retain a 
tincture of acidity, which obliges us 
to wash ’em frequently in order to 
Edulcoration, viz. Because they ha- 
ving

(44)
ving the sharp extremities of the 
acid particles fasten’d in their pores, 
cannot but imbibe and derive from 
them, an acid or corrosive qua- 
lity; which is not to be otherwise 
remov’d than by frequent washing 
in Water; for these sting-like Par- 
ticles being easy to be dissolv’d in 
a large quantity of Water, do dis- 
perse themselves up and down the 
same; and, thus their force being 
dis-united and interrupted, cannot 
but be impair’d. And the like 
reason serves ’em to solve the phe- 
nomenon of a Menstruum, which 
tho highly Acid or Corrosive yet 
loses a great part of its Acidity and 
Corrosive Nature by the Precipitati- 
on of the dissolved Mettal, insomuch 
that it becomes useless and unapt for 
dissolving other Metals; for the 
edges or points of the Acid Particles 
being broke or made blunt by the 
force of the precipitating Liquor, 
they cannot pierce the substance of a 
solid Body.
There 

(45)
There is yet a third opinion of 
the precipitation of dissolv‘d  Bodies 
by the affusion of a new Liquor, 
viz. That it is merely owing to the 
freedom of their parts, they being 
dis-engaged of their former Fetters, 
while the Acid or Alkaline Parti- 
cles of the Menstruum have a greater 
inclination to unite with the Body 
of the new Liquor, and thus are 
tempted to set at liberty the dis- 
solved prisoner; and from this Hy- 
pothesis they frame reasons for ex- 
plaining the vertues of precipitated 
Alkalies dissolv‘d in Acids; and of 
Acids dissolv‘d in Alkalies. But 
others choose yet a different method 
of unfolding the nature and disposi- 
tion of the Menstrua that forsake 
the embraces of the dissolv‘d Body, 
to joyn themselves with the Liquor 
that is pour‘d upon ’em; which is 
calculated from the Laws of Moti- 
on; for that all Bodies whatsoever 
have a natural inclination to bend
to

(46)
to that side where they find the 
least resistane, or where they can 
move with greater ease & freedom. 
Hence the Acid Menstrua, when 
mov‘d and agitated by the afflux of 
an Alkaline Liquor, do abandon 
their metallick companions, and co- 
ver the embraces of the Alkalie; 
and è contra; For they meet with 
less resistance, and a more patent 
way, in moving towards the 
same. But withal I think it not 
improper to take notice of the acti- 
on of the ethereal matter, which 
having once found entrance into the 
dissolved Body, and afterwards up- 
on the affusion of a new Liquor 
meeting with a less resisting sur- 
face, and enlarged passages, rushes 
in, in greater abundance, and beats 
down the resisting Particles towards 
the bottom. 
Having thus taken a general sur- 
vey of Fermentation and its effects, 
I should next in order proceed to
its
 

(47)
its Specifick differences that are 
observ‘d in Minerals, Vegetables, 
and Animals (nay, and Meteors 
too) and so view the changes, al- 
terations, generations, and Corrup- 
tions that the threefold family af- 
fords. But seeing that the nature 
of a Feaver, which is a Species of 
Fermentation, may be sufficiently 
gather‘d and understood from what 
has been premis‘d of Fermentation 
in general; and that, what is here 
emitted, is discours‘d of at large by 
Willis, and several other Authors, 
who have employ‘d their Pens pur- 
posely upon that Subject; I shall 
now confine my self to that parti- 
cular Species of Effervescency or Fer- 
mentation, which among Physici- 
ans is denominated a Feaver; and 
which is the chief or only object of 
this Treatise. 
And that I may convey to the 
Minds of my Readers some Idea or 
Notion of what it is, I agree with
the 

(48)
the wiser Physicians in defining it 
to be, An Inordinate and Expansive 
(but permanent) Motion or Effer- 
vescency of the Circulating Humours 
and Mass of the Blood, which alters and 
and accelerates the pulse beyond its 
natural temper, and raises an exces- 
sive heat, either in the whole Body, or 
in its principal parts. But for the 
fuller understanding of this defini- 
tion, we are to call to mind what 
has been said in the beginning of 
this Treatise, viz. that the Blood 
do‘s truly ferment within us, and 
circulate; in which twofold Moti- 
on our natural Heat and Life do‘s 
consist; and that this Fermentation 
is said to be convenient and agree- 
able to our Natures, so long as it 
continues moderate; that is, so long 
as it is fit for performing the functi- 
ons which do either mediately or 
immediately depend upon the same; 
or, to express my self more clearly, 
so long as the constituent Elements
of 

(49)
of the Blood which are in themselves 
different and varying from one ano- 
ther, do by vertue of their mode- 
rate or well temper‘d Heterogeneity 
undergo a gentle and soft commo- 
tion, by the easy and peaceable en- 
trance of the ethereal matter; and 
are exactly mix’d and incorporated 
with one another: Which smooth 
and agreeable disposition is mighti- 
ly advanc‘d by the circular motion 
of the Blood, that depends upon a 
lively compression of the Heart in 
its Systole, and imparts both heat 
and nourishment to all the Body. 
For it is now accounted beyond all 
peradventure, that the Blood ,as 
well as other Bodies, consists of di- 
vers and varying parts, which are 
of different figures, and differently 
to be accounted of; some of ’em 
being Spirituous, very subtil and 
moveable; some Sulphureous or Bi- 
lious; some Saline both Volatile 
and Fix‘d; some Watery or Serous, 
D and

(50)
and in Fine, some Tartareous or 
Earthy; all which, as they are dif- 
ferently combin‘d or joyn‘d to- 
gether, or predominant one a- 
bove another, do convey dif- 
ferent Constitutions to the Blood, 
and thus are the cause of the diffe- 
rence of Temperaments in a Natural 
State, and of Diseases in a Preter- 
natural. The truth of this Plura- 
lity of differing parts in the Blood, 
is not only confirmed by the ana- 
lysis or resolution of the Blood, 
which presents to our view the 
above-mention‘d Elements or Prin- 
ciples; but is demonstrable from 
Reason and Experience; for the 
saltness of the Urine, Serum, and 
Spittle do‘s certainly prove the pre- 
sence of Salts in the Blood. The 
choler, being of a yellow sulphureous 
colour, which is filtrated through 
the substance of the Liver, and is ea- 
sily inflammable in several Bodies, is 
an evident instance of the sulphure- 
ous

(51)
ous particles: The small Spirits 
that are strain’d through the Cor- 
tical part of the Cerebrum, and 
whose existence is acknowledg’d 
by all, do necessarily infer some 
subtile, moveable, and spirituous 
matter, of which they are genera- 
ted: The Urine, Sweat, Tears, 
nay, and the very Liquidity of the 
Blood, do openly proclaim a Water 
or Phlegm in the same. And the 
grossness or coagulation of Blood 
drawn out from the Veins, nay, 
the very Stones that are ingender’d 
within our Bodies, do clearly sig- 
nifie that there be some terrestrious 
or earthly Particles in the Blood. 
In fine, being that whatever goes 
to our nourishment is a needful in- 
gredient into the composition of 
our Bodies, and that we indifferent- 
ly seed upon Spirituous, Sulphure- 
ous, Saltish, Watery, and Ter- 
restrious things, we have all rea- 
son to conclude that there are par-
D2 ticles 

(52)
ticles or substances within us of the 
same qualities. For the Food we 
receive cannot make any chyle, 
but what must partake of the 
like Principles as it has in it 
self; tho’ perhaps they be not so 
gross; and the Blood which is 
made of that chyle must be of the 
same nature. Moreover, the chyle 
which continually runs into the 
Blood for repairing its losses, and 
which contains in its Bosom many 
different particles disagreeing with 
those in the Mass of the Blood; 
and likewise the Lympha, which 
returns again to the Blood from 
the Glandules, where it was sepa- 
rated; and which is impregnated 
with an Acid quality, as we see by 
its extinguishing of Mercury; these 
two, I say, are very serviceable in 
maintaining and preserving the Fer- 
mentation of the homours in our 
Body. For the Chyle that insen- 
sibly drops into the Blood in the
Sub- 


(53)
subclavian Vein is not altogether ho- 
mogeneous or uniform: And in that 
condition circulating round with the 
Blood thro’ the Heart and the Blood 
Vessels do’s by the irregularity and 
disproportion of its parts raise a 
Fermentation, whence it is chang’d 
from Chyle into Blood; and be- 
cause the Sulphureous and Balsa- 
mick parts are dissolv’d by the sharp 
Salt of the Blood, it loses its white 
milky colour, and becomes red. 
But the Lympha being stuff’d with 
Acid Particles is a natural Enemy 
to the Alkaline Bile that is lodg’d 
in the Blood, and do’s as forcibly 
cause a Fermentation of the Blood, 
as the mixture of an Acid with an 
Alkali is known to do in other in- 
stances. And as to the Chyle’s 
encreasing and advancing the Fer- 
mentation of the Blood, after being 
mix’d with the same, we need no 
other proof but that of the Body’s 
becoming hotter, and the Pulse
D3 beat- 


(54)
beating faster, about two or three 
hours after eating; which is the 
precise time that the Chyle is drop- 
ping out of the Ductus thoracicus 
into the Subclavian Vein, and dif- 
fusing it self along with the Blood 
through the whole body. 
But the Sulphureous and Spiritu- 
ous parts that are predominant in 
the Blood (as in all other Bodies 
that are liable to freqent Fermen- 
tations) are highly conducive for 
exalting its natural Fermentation, 
which arises from the mutual strife 
of its internal Principles, and the 
reciprocal Jarrs of the Heterogene- 
ous Particles both in the Blood, 
Lymphe, and Chyle; for they be- 
ing easily moveable, and being once 
put in motion by the ingress of 
the ethereal matter, are very active 
in attenuating and subtiliating the 
gross resisting parts, that I menti- 
on’d before, while treating of Fer- 
mentation in general. Hence we
observe

(55)
observe that in a hot fiery tempera- 
ment where the Blood is hot, thin 
and sprightly, and full of spirituous 
Sulphur, it is much more Ferment- 
ed , than in other temperaments 
where Phlegm, Earth, or such like 
passive Principles do obtain a sove- 
reignty over these active ones, and 
entangle or dilute ’em too much: 
As also that the exaltation of the 
Sulphureous parts of the Blood is 
generally alledg’d for the cause of 
all Feavers, because they are more 
capable to diffuse a Feaverish heat 
through the Body than their other 
fellow companions. So that a na- 
tural or healthy Fermentation is 
such as is moderate and equal, for 
the reasons above-mention’d: But 
a Preternatural and Sickly one is 
such as is either too slow pac’d and 
dull, which is the cause of cold di- 
stempers, obstructions, cachexia’s or 
ill habit of Body, Green sickness, 
Melancholly, &c. or too swift and 
D4 violent

(56)
violent, and attended with too 
great commotion of the Blood and 
its Elementary Principles, which 
last is justly accounted the cause of 
all Feavers; so that a Feaverish 
Fermentation do's not differ from 
a Natural one, but gradually or in 
less and more; and the same causes, 
as they are more or less intense in 
their actions, are equally the Au- 
thors both of a natural and preter- 
natural Fermentation. 
And for so much as our present 
discourse centers upon Feavers, I 
am now to explain apart every 
word of their definition: In the 
first place a Feaver is said to be 
An inordinate and expansive Motion; 
which words serve to represent its 
Genus; for ’tis a preternatural mo- 
tion, and truly Fermentative, see- 
ing it possesses the same very qua- 
lities that accompany the Fermen- 
tations of other Bodies. In the 
next place ’tis said to be a Perma-
nent 


(57) 
nent Motion; that is, such as lasts at 
least for a day or two; to distinguish 
it from an accelerated circulation of 
the Blood, that follows upon run- 
ning, or such other violent Exer- 
cises as procure an intense heat and 
sweating over the Body: For that 
estuation or tumult in the Blood 
cannot be call’d Feaverish or 
Morbifick, since our Pathological 
Writers do unanimously agree that 
’tis an essential property of a di- 
sease to be permanent and abiding 
in the Body, and not to pass over 
of a sudden. Moreover, this Fea- 
verish Motion is such as accelerates 
the pulse beyond its natural Temper, 
and produces a change in the same; 
which is sufficiently attested by 
daily Experience; for we see that in 
all Feavers the Pulse is much more 
frequent than ordinarly; and for the 
most part ’tis otherwise alter’d from 
what it uses to be in a natural 
State, becoming either higher, ful-
D5 ler, 

(58)
ler, unequal, or intermitting; all 
which are only owing to the im- 
moderate Fermentation, which al- 
ters the constitution of the Blood, 
attenuates and dis-engages its Par- 
ticles, and renders the animal Spi- 
rits more moveable, whence ensues 
a quicker and more violent Systole 
of the Heart; for the Blood and 
animal Spirits are the undoubted 
and only cause of the constriction 
of the Heart, and of all other mus- 
culary motion. The last words of 
the definition import that, It raises 
an excessive heat either over the whole 
Body or in its principal parts; which 
generical quality is equally accom- 
modated to Feavers of all sorts, 
whether they be such as procure an 
universal heat over the Body; or 
such as only cause an excessive heat 
in the inward Parts or larger Ves- 
sels, but leave a sense of horrour 
and cold in the extream parts or 
habit of the Body; as the lypery,
cold 


(59) 
cold and trembling Feavers; and 
this sense of cold is merely owing 
to the pricking and grating of a 
Salt Serum upon the Musculary 
Membranes: This last clause of 
the definition serves likewise to 
distinguish a Feaver from several 
other Constitutions of the Body 
in which the beating or pulse of 
the Arteries is accelerated, but is 
not feaverish; as in the Green 
Sickness, Cachexia, and in the 
Pangs of Death; for in such cases 
the Blood and Spirits being vitiated 
do but faintly contract the Heart, 
so that the space it moves in be- 
shorter, its pulsation returns the 
oftner. I shall not here stay to 
refute the definition which the An- 
cients gave of a Feaver, as being a 
Preternatural Heat, originally kind- 
led in the Heart, and from thence 
diffus'd through the Arteries over the 
whole Body: Since ’tis sufficient to 
remark that ’tis neither adequate,
exact, 


(60)
exact, nor clear; nay, that it ra- 
ther explains the effects of a Fea- 
ver, than its essential and first at- 
tributes. Besides, The Ancients 
were hugely mistaken in taking a 
Feaver to be only a Disease in so 
far as ’twas communicated to the 
Heart, which they thought was 
the only true Living part; for they 
neither allotted the Blood any man- 
ner of Life, nor would they own 
it for a part of the Body; the 
falshood and absurdity of which 
position cannot but be obvious to 
the merest novices in Physick. 
This our Definition if throughly 
weigh’d and well understood re- 
moves all further doubt, or suspense, 
of the proper and immediate sub- 
ject of a Feaver, which is certainly 
the Mass of the Blood and Humours 
circulating in the Blood Vessels, 
for that is only capable of Fermen- 
tation. Whence we are led to 
discover the Error of the Ancients
in 

(61)
in determining the Preternatural 
Heat of an Ephemera or Day-Feaver, 
to be only seated in the Spirituous 
Parts of the Blood, as if the rest 
of its Mass did not partake of the 
change as well as they. Or as if 
the Solid parts could first conceive 
a heat of themselves, and then com- 
municate it to the Blood and Hu- 
mours; whereas all Heat, whether 
Natural or preternatural, depends 
solely upon the Circular and Fer- 
mentative Motions of the Blood. 
Both ancient and modern Phy- 
sicians have disagreed in giving the 
divisions of Feavers; some divide 
’em into Continual and Intermitting; 
others into an Ephemera, Putrid and 
Hectick; others into not Putrid, 
Putrid, and Pestilential: But we 
shall not confine our selves to the 
method and divisions of other Au- 
thors, (which if any covet to know, 
he may understand from their own 
Writings) accounting it more pro-
per 

(62)
per to follow the simple and plainer 
way in dividing ’em into Essential 
and Symptomatical. The Essential is 
that whose cause is originally lodg’d 
in the Blood, and has no depen- 
dance upon any other distemper, 
or affected part of the Body. The 
Symptomatical Feaver, is so call’d, 
because ’tis only a Symptom of ano- 
ther distemper or disposition; and 
whose immediate cause is not ori- 
ginally plac‘d in the Blood, but 
deriv’d from some affected part, 
and so communicated to the 
Blood. Of the first sort are the 
Burning, Malignant, Continual, 
and Intermitting Feavers; in which 
the Effervescency of the Blood is 
produc’d by a cause bred in its own 
bosom; and therefore are call’d 
Essential. But such Feavers as 
follow upon Inflamations and Ul- 
cers of the parts, are of the second 
Category; for the Heterogeneous 
Miasma’s that are confus‘d with 
the

(63)
the circulating Blood, when repair- 
ing to it from the Ulcer, do 
raise the Preternatural Fermentati- 
on, so that it do‘s not deserve the 
name of an Essential or Primary, 
but that of a Secondary or Sympto- 
matical Feaver. An Essential Fea- 
ver (that is, such a one as arises 
immediately from the indisposition 
of the Blood, without the mediation 
of any other affected part) is sub- 
divided into a Continual and In- 
termitting. The Continual is that 
which from its first attacking of 
the Sick Person, never relents, or 
gives o’er, till the morbifick cause 
be expell‘d either by sweating or 
some other Evacuation; or till the 
Heterogeneous Particles contain‘d 
in the Blood (that are the source 
of the Preternatural Fermentation) 
be so subdu‘d and vanquish‘d, that 
the immoderate commotion of the 
Blood ceases thereupon, without 
any fix‘d or constant Period of its 
return.

(64)
return. But a Feaver is said to be 
Intermitting, when the morbifick 
cause do’s not continually act upon 
the Blood; but only by certain fits 
with intervals of Remission betwixt 
’em; so that sometimes the sick Per- 
son is all over feaverish, at other 
times perfectly free of it. And the 
same very effect or end (viz. the 
dispersing and subduing the Hete- 
rogeneous parts) which in a conti- 
nual Feaver is compass’d by one 
continual, protracted Paroxysm, 
is brought to pass in the inter- 
mitting by several repeated Pa- 
roxysms, which for the most part 
observe a constant and fix’d Period, 
of returning. A continual Feaver 
is sometimes putrid; sometimes 
not putrid. But an Intermitting 
is always attended with Putrefacti- 
on. But by Putrefaction I under- 
stand (as do all the wiser Physi- 
cians) a loosening of the System 
of the Humours, and a separation
of 


(65)
of the constituent Principles of the 
Blood, so that its texture or frame 
being altogether unlock’d, or disjoin- 
ted, the principal parts do fly away. 
A Continual Feaver is said to be not 
putrid, when the Feaverish Fer- 
mentation of the Humours do’s not 
sensibly loosen the union or mix- 
ture of their principles, or infer 
any remarkable dissolution of the 
texture of the Blood; but while 
’tis call‘d not putrid, we are not 
to understand the words so strictly 
as if the Blood underwent no man- 
ner of dissolution, or suffer‘d no 
separation of its Principles, for ’tis 
impossible that an immoderate Fer- 
mentation of the Mass of the Blood 
should not entail some change or 
other. These Imputrid Feavers are 
either such as last but for a day, 
and are call‘d Ephemera‘s or Day- 
feavers; deriving the etymology of 
their name from a certain Animal, 
call’d Ephemeron, the length of 
whose

(66)
whose Life is said not to surpass 
that of one day; or are such as 
reach to the second or third day, 
and were known among the Anci- 
ents by the name of a Protracted 
Ephemera, or a Synochus not Putrid. 
On the other hand, a Continual 
Feaver is call‘d Putrid, when the 
Agitation or Commotion of the 
Humors lodg‘d in the Blood Ves- 
sels is so violent and lasting, that 
the Blood do‘s thereby suffer the 
loss of its chiefest parts, the dissolu- 
tion of its Contexture, and the se- 
paration or divorcing of its Prin- 
ciples. And this Putrid Feaver is 
either Acute, which quickly runs 
its course and comes to an end, by 
reason of a great abundance of 
active Principles that enliven the 
Fermentative Motion of the Hu- 
mors; or Chronical and Lingring, 
in which the Fermentation tho’ 
Preternatural is but dull and lazy, 
by reason of the scarcity or defici- 
ency

(67)
ency of Sulphureous and Spirituous 
Particles. Or else it is Hectick; for 
a Hectick Feaver is justly account- 
ed Putrid, when ’tis become habi- 
tual, and the whole Crasis of the 
Blood vitiated, so that ’tis not 
fit for nourishing the parts; whence 
ensue the leanness and consumption 
of the Body, that are the visible 
Consequents of a Hectick. But in 
respect of the greater or lesser de- 
cay and loss of the chief Particles, 
or the greater or lesser dissolution 
of the Blood, and separation of its 
Principles, some Feavers are said to 
be simply Putrid, others Malignant, 
in which the dissolution of the 
Blood is very remarkable; and o- 
thers Pestilential, in which the disso- 
lution and separation is so great, that 
a greater cannot be. The simple 
Putrid Feavers, that is, such as are 
attended by a moderate dissolution 
of the Blood, were divided among 
the Ancients, into Bilious, Phleg-
matick, 

(68)
matick, Melancholick and Sanguine, 
from the various exaltation and 
predominancy of any one Humor 
in the Body above the rest; and 
in like manner some of the modern 
Writers divide ‘em into Bilious, 
Sanguine, Lymphatick, &c. But 
these divisions are of little or no 
importance; nor ought we to be- 
lieve with the Ancients that either 
the Choler, Phlegm or Melancholy 
can Putrify alone, and by vertue 
of that its peculiar Putrefaction, 
give name to the Feaver; nor with 
the Moderns, that only the Choler 
or Lymphe can Ferment, or be the 
cause of Fermentation; for that 
work belongs rather to the whole 
Mass of the Blood, than to the 
Bile or Lymphe apart; and there- 
fore all such Feavers are more pro- 
perly Sanguine, than Bilious or Lym- 
phatick. 
Besides the differences of Conti- 
nual Putrid Feavers already spoken
of; 

(69)
of; there are several others no less 
worthy to be taken notice of; for 
some are simple, and of one even 
temper (which sort of Feaver in 
the Language of the Ancients was 
call’d Acmastica, or Homotonos) 
when the accession is equal, and 
oppresses the patient always after 
one manner, detaining the Humors 
in the same degree of Putrefaction 
from the beginning to the end- 
ing, extending its Paroxysm to se- 
veral days without any Intermis- 
sion or Exasperation whatsoever. 
Sometimes this simple Feaver 
encreases gradually, or augments 
its strength by a successive Putre- 
faction of the Humors; and is call’d 
Epacmastica in opposition to the 
Paracmastica, which decreases by 
degrees, by a gentle and insi- 
ble decay of the first Putrefacti- 
on; which follows upon the sub- 
duing, dispersing, or evacuating 
the Heterogeneous and Fermenta-
tive 

(70)
tive Particles that first gave rise to 
the same. Other Continual Pu- 
trid Feavers are compounded; for 
tho’ they be continual, yet they 
are liable to Periodical Exasperati- 
ons and Remissions, and thus seem 
to be compounded of a continual 
and intermitting joyn’d together; 
they are call’d either Continual 
Quotidians, Tertians or Quartans, 
as the Fits return either every 
day, or every other day, or third 
day, &c. But if several Fits return 
in one set day, whether second, 
third, or fourth, then the Feaver 
is yet more compounded, consisting 
of a simple continual and a double 
Tertian, or a double or treble Quar- 
tan, according to the various Cor- 
respondence of the Fits to one ano- 
ther. And if a Feaver be both 
continual and liable to Quotidian, 
Paroxysms, or is compounded of a 
simple continual Quotidian, and 
Intermitting; and withal have Fits
every

(71)
every third day, with Paroxysms 
resembling those of a Tertian Fea- 
ver, and Corresponding orderly to 
one another, then ’tis call’d a Semi- 
tertian; that is, a compound of a 
simple continual, a quotidian and 
tertian intermitting Feaver; which 
the Ancients have made so much 
noise of. Having thus describ’d all 
the several sorts of Continual Putrid 
Feavers, we shall in the next place 
relate the divisions of the Intermit- 
ting ones. And in the first place 
some of ’em are orderly, and keep 
to their periodical turns, which are 
constant and determin’d to an hour; 
others are erratick, inconstant, and 
disorderly, whose paroxysms ob- 
serve no order of days in their re- 
peated accessions, nor any fix’d cor- 
respondence to one another; and 
if these Paroxysms do immediately 
succeed to one another, as if the 
second should begin upon the ter- 
mination of the first, ’tis call’d a 
Subin-

(72)
Subintrans. The intermitting or- 
derly Feaver is subdivided into sim- 
ple and compound; ’Tis said to be 
simple when it do’s not return ost- 
ner than once in one day; and 
from the mutual distance of the 
days, whether the very next, third 
or fourth, are the divisions taken 
of Quotidian, Tertian, Quartan, 
Quintan, Sextan, &c. And not from 
the variety of the Humors, viz. 
Phlegm, Bile and Melancholly, as 
the Ancients would have it, who 
thought that the Putrefaction of 
the Phlegm was the cause of Quo- 
tidians, that of the Bile of Terti- 
ans, and Melancholy of Quartans; 
which opinion cannot but appear 
to be unreasonable and groundless 
to any considering Person; for since 
they allow’d but four Humors in 
the Body, how could they explain 
the Natures of Quintans, Sextans, 
&c. Wherefore the difference of 
Intermitting Feavers is rather ow-
ing 

(73)
ing to the difference of their Peri- 
ods than any other cause. And 
indeed I know no reason why the 
double Tertian of the Ancients 
which recurrs every day, and their 
triple Quartan which observes the 
same Period, should not be reckon’d 
among the Quotidians; especially 
since they themselves must needs 
acknowledge that a Feaver is call’d 
Quotidian when the Paroxysm re- 
turns every day; and in like man- 
ner Tertian, Quartan, or Quintan, 
when it returns every third, fourth, 
or fifth day. An Intermitting Fea- 
ver is said to be compounded, when 
the Paroxysm returns several times 
in one day, as if twice, thrice, &c. 
and as the day on which it repeats 
these fits is either the next, third, 
or fourth in order, so ’tis call’d a 
double or triple Quotidian, Tertian, 
Quartan, &c. And these are the dif- 
ferences of Essential Feavers; unto 
which the divisions of the Sypmto-
E matical 

(74)
matical succeed to be related. 
Symptomatick Feavers, as well as 
Essential ones, are divided into Pu- 
trid and not Putrid: They are said 
to be not Putrid when the union 
or mixture of the Principles in the 
Blood is not much loosen’d or un- 
lock’d, nor its contexture sensibly 
dissolv’d; such are the Feavers that 
are wont to attend Colick Pains, 
Head-aches, Tooth-aches, Disente- 
ries, &c. in which the pain causes 
such a disorderly and irregular mo- 
tion of the Spirits, that they con- 
tract the Heart more frequently, 
and thus raise a commotion in the 
Mass of the Blood, and awaken or 
stir up the Heterogeneous Particles 
that do always in some measure 
lodge in the same. In like manner 
they are said to be Putrid, when the 
Blood is more oppress’d; and the 
bond of its Principles sensibly un- 
lock’d; as in the Feavers which 
arise from the Inflamations of seve-
ral 


(75)
ral parts of the Body, or Ulcers and 
Impostumes: For the Putrid, Hot 
and Fermentative Particles which 
proceed from the Inflam’d or Ul- 
cerated part are mix’d and confus’d 
with the Blood as it circulates 
through it, which they are very 
Contrary and Heterogeneous to, 
insomuch that they put it into a 
Fermentation, and dissolve its frame 
and constitution. Of the Sympto- 
matical Feavers which are not Pu- 
trid some are Ephemera’s or Day- 
feavers, that are not extended be- 
yond a day or two at most, by 
reason that the Blood is less dispos’d 
for a Preternatural Fermentation. 
Others endure for many days, by 
reason of the contrary cause. But 
as to the Symptomatical Putrid Fea- 
vers, some are acute and short, such 
as the Feavers which owe their ori- 
ginal to Inflamations, which quick- 
ly terminate, and for the most part 
without any danger: Some are
E2 long

(76)
long and chronical, extending to 
several Months, of which sort 
are those flow Hectick Feavers 
which accompany the Ulcers and 
Imposthumes of the inward parts, 
whose corrupted and putrified Par- 
ticles are insensibly communicated 
to the Blood, and by a flow and 
gentle pace dissolve its Mass, with- 
out that sensible Effervescency or 
Boiling that attends other Feavers, 
by reason of a greater abundance 
of Heterogeneous Particles either 
hatch’d in the Blood, or imparted 
to it from elsewhere. 
But to prevent all mistake, I 
must own that while I speak of 
Symptomatick Feavers accompany- 
ing Inflamations, I do not mean that 
they are always secondary, and sub- 
sequent to the Inflamation; for 
sometimes they are primary and 
essential; and in that case the In- 
flamation is a Symptom of them, 
by reason that in a violent Fermen- 
tation

(77)
tation of the Blood, some of the 
Blood Vessels may be too much 
open’d or broken, whence ensues an 
Expansion or Extravasation, or a 
croud of Humors repairing to the 
place, according to its various dis- 
position; and either of these cause 
an Inflamation. But the Sypmto- 
matical Feavers that follow and de- 
pend upon an Inflamation may un- 
dergo serveral considerable differen- 
ces, according as the constitution of 
the Blood which causes the Inflam- 
mation is thinner or thicker; with 
respect to which difference, some 
are call’d Erysipelatodes, others 
Phlegmonodes, &c. And such as are 
rais’d by an Ulcer or Impostume 
are justly call’d Purulent or Pu- 
trify’d, because the part of the Bo- 
dy Inflam’d is Corrupted and Putri- 
fy’d by a Gangrene or Sphactle, and 
thus communicates its Poysonous 
Particles to the Blood. These are 
the principal and most considerable
E3 dif- 

(78)
differences of Essential and Symp- 
tomatick Feavers; unto which o- 
ther Writers add several others, 
tho’ of less importance and more 
accidental, they being taken from 
the various symptoms and accidents 
that are wont to attend ’em; thus 
because of the burning Heat, and 
unquenchable Thirst that accom- 
panies some Feavers, they are call'd 
Causons or Burning Feavers. Others 
are call’d Lypyriœ and Trembling 
Feavers, by reason of the cold that 
possesses the external parts, while 
a violent heat rages within. Some 
are call’d Purple or Petechial Fea- 
vers, from the Exanthemata or red 
spots that appear in the Skin; some 
Horrifick from the frequent horror 
and shivering, or the successive re- 
turns of cold and heat: Some 
Swoonding Feavers, from their fre- 
quent faintish and swoonding Fits; 
Some Worm Feavers, from the 
Worms that sculk in the Guts, and 
joyn

(79)
joyn sorces with the Feaver; some 
Milk Feavers from the Milk that is 
gather’d in the Breasts, which oft- 
times gives rise to a Feaver. Some 
Catarrhal, Arthritick or Rheumatick, 
from the Catarrhs, and other Sym- 
toms or Diseases that attend ’em. 
Some Convulsive, Vomiting, Gri- 
ping, Hungry, &c. from the 
like Symptoms. Some Assodes or 
Loathing, from the uneasiness of the 
Stomack and vomiting. Some sweat- 
ing or Elodes from the continual 
Sweating. And to conclude, others 
are call’d Epialœ from the frequent 
accession of heat and cold to one and 
the same part. All which are pur- 
sued at large by Sylvius. 
Having thus related the several 
differences of Feavers with all pos- 
sible accuracy, it remains now that 
we should with equal application 
enquire narrowly into their causes. 
But ‘tis not to be expected that we 
can discourse apart of all their se- 
E4 veral

(80)
veral Species or kinds, with an e- 
qual length; for such a Treatise as 
that would swell big enough for a 
whole Volume: Our business is to 
explain the causes of the most prin- 
cipal, and remarkable, from which 
the causes of the others may easily 
be understood: And in the first 
place to open up this matter more 
clearly, ’tis to be remark‘d that 
the opinions of the ancient and 
modern Writers concerning the cau- 
ses of Feavers are very different; 
which we shall take a view of, in 
order to judge, which of the two 
may best merit our Belief. 
To begin then with an Epheme- 
ra or Day feaver, which is the first 
Species of Feavers mention’d above, 
the Ancients thought it proceeded 
from the agitation of the Spirits in 
the Blood. But an Hectick they 
deriv’d from an imbred heat first 
augmented in the solid parts, and 
transmitted by them to the Blood, 
as


(81)
as it passes in its Circulation. 
The Modern Writers have fol- 
low’d much another method in ex- 
plaining the causes of Continual, 
Intermitting, Putrid, and not Pu- 
trid Feavers, &c. for they have cast 
out of Doors the Malignant and 
Occult Qualities, the motion of the 
Stars, and the fourfold nourishing 
Humor: And having discover’d 
the circular motion of the Blood 
from the Arteries to the Veins 
through the whole Body, occasi- 
on’d by the successive constriction 
and relaxation of the Heart, do 
look upon the Blood as consisting 
of the above mention’d Principles, 
and abounding with spirituous and 
active Particles, or as stuff’d with 
Heterogeneous Superfluities which 
are to be expell’d out of it, to be 
the cause of all Feavers; unto which 
they add some Juices lately disco- 
ver‘d by Anatomy, which either 
mediately or immediately are wont
E5 to

(82)
to empty themselves into the Blood, 
as the Chyle, Lymphe, and Pan- 
creatick Juice. The most noted 
of these Modern Writers are Willis 
and Deleboe Sylvius; who have 
fram‘d new Hypotheses peculiar to 
themselves: Of which neither the 
one nor the other ought to be quite 
rejected, nor totally imbrac‘d; for 
though they advance several points 
very likely to be true, yet they 
have others very improbable. As 
for instance, Sylvius asserts that the 
Pancreatick Juice stop‘d in the la- 
teral ducts of the Pancreas or Sweet- 
bread, by a viscid Phlegm, do’s at 
certain intervals break through the 
Phlegm, and run into the Duodenum, 
and thus causes Intermitting Fea- 
vers; which is sufficiently disprov’d 
by answering that ’tis a ground- 
less Assertion, that bears no colour 
or shew of Truth. But as to the 
Bile and Lymph which he gives 
for the causes of Continual Feavers, 
no


(83)
no Man of solid Learning can dis- 
allow of it; for the Lymphe 
on one side abounding with Acid 
Particles, and the Bile on the 
other impregnated with a Lixivi- 
ous Salt, are the two fittest Hete- 
rogeneous Bodies, either to pre- 
serve and cherish the natural Heat 
and Fermentation of the Blood, 
when in a moderate temper; or to 
raise a preternatural and feaverish 
Fermentation, when either of ’em 
is exalted beyond their due propor- 
tion. In like manner Dr. Willis’s 
opinion of the cause of Continual 
Feavers, which he alledges to be 
the fierceness and rage of the Spi- 
rits and Suplhur in the Blood, is 
by no means to be approved of; 
for tho we cannot deny that these  
two principles are exalted in the 
most part of Feavers, and by con- 
sequence being very moveable may 
forward the preternatural motion 
of the Blood; yet it seems originally
to 


(84)
to be owing to the disproportion 
and heterogeneity of the particles 
of the Blood, or to the irregular 
and disorderly constitution of the 
Lymphatick Juice that is continu- 
ally discharg‘d by the Glandules 
into the Blood; for their irregular 
and disproportion‘d Figure renders 
their mixture or confusion with the 
Blood very difficult, and affords a 
free and open Door for the ingress 
of large quantities of ethereal mat- 
ter, which agitates and puffs up the 
grosser particles of the Blood that 
stand in its way. Moreover there are 
some Feavers, as an inveterat He- 
ctick in which the Spirits are ve- 
ry low; so that it is inexplicable 
how by the affusion or mixture 
of a Heterogeneous Body with the 
Blood, or any other Liquor, the 
Sulphur and Spirits should all of 
a sudden rise up and endeavour to 
fly away, and thus create an Effer- 
vescency or Fermentation (as Dr. 
Willis

(85)
Willis imagines.) For if their ex- 
altation and measure was so mode- 
rate and regular as not to undergo 
a Fermentation before the confu- 
sion and mixture of the Heteroge- 
neous Body, why should its arri- 
val introduce such a sudden change? 
But withal ’tis certain and incon- 
testable that (as he says) the cause 
of several Intermitting Feavers may 
be the crudity of the nutritious 
Juice or Chyle, occasion’d either 
by some defect in it self, or by the 
corruption of the ferment of the 
Stomack; and sometimes the de- 
prav’dness of the Blood, when it 
degenerates from the wonted Fi- 
gure and Situation of its parts, 
may give rise to the imperfection 
and crudity of the Chyle, and so 
cause the Feaver; for when the 
Chyle is in a natural disposition, and 
continually joyning it self to well 
temper’d Blood, it certainly produ- 
ces a natural and friendly Fermen-
tation
 


tation in the same; as is evident 
from the Sprightlyness of the Pulse, 
the encrease of heat, retrieving of 
Strength, and the more vigorous 
motion of the Spirits some hours 
after eating: And by consequence 
when it swerves from its natural 
State, and is crude or unconcocted, 
or is mix’d with degenerous and 
depraved Blood (that is, whose 
Constitution is become auster, acid, 
or sharp; or any other way vitia- 
ted by the various Combination and 
Predominancy of its several Prin- 
ciples, or the perverse disposition 
of its Particles) it imparts to the 
Blood a higher and more feaverish 
Fermentation, and thus procures 
an intense heat over the whole 
Body; which (as was said alrea- 
dy) is chiefly owing to the Hete- 
rogeneity and Disproportion of the 
Chyle and Blood, that affords an 
entry to greater measures of ethe- 
real matter, which raises a stir and
tumul-

(87)
tumultuous commotion in the in- 
sensible particles. This Supposition 
concerning the cause of intermit- 
ting Feavers is built upon the Do- 
ctrine of Sanguification, which 
consists in a dissolution of the 
fat and sulphureous parts of the 
Chyle, by the sharp and lixivious 
Salt of the Blood; and by raising 
a heat which changes its white 
colour into a red. For Chymical 
Experiments do sufficiently evince 
that fat and sulphureous things can- 
not be dissolv’d but by what is 
sower or sharp; and that their so- 
lution entails upon ’em a ruddish 
colour. Now the natural dissolu- 
tion of the Chyle is done by a slow 
and gentle commotion of the con- 
stituent parts of the Blood, occasi- 
on’d by the mutual and agreeable 
proportion of the Chyle and Blood; 
but when they are Heterogeneous, 
the Motion is more violent and dis- 
orderly, for both Liquors bereav’d 
of


(88)
of the due and wonted proportion 
and figure of their parts, cannot easi- 
ly mix or combine together; and 
therefore when they justle one a- 
gainst another, they must needs 
raise an Effervescency greater than 
the Natural, and thwart the assimi- 
lation and commutation of the chyle 
into the Blood; for unless there be 
a fit proportion betwixt the agent 
and patient, there shall still remain 
some parts of the Chyle that by 
reason of their crudity and grosness 
are not converted into Blood, but 
swim in its Mass like so many He- 
terogeneous Bodies, that while their 
number is small and unfrequent are 
so entangl’d and kept under by the 
Blood that they cannot excite the 
feaverish Paroxysm, till in the pro- 
gress of a certain time their 
number be augmented sufficiently 
for performing that Office; like 
some Liquors that do not ferment, 
but when mix’d in certain deter- 
min’d

(89)
min’d quantities. And these crude 
parts of the Chyle cannot be ex- 
alted, and assembled in a sufficient 
quantity, till after several digesti- 
ons in the Venticle, and conversi- 
ons of Chyle into Blood: But as 
the first Concoction is more or less 
perverted, or as the Blood swerves 
more or less from its natural 
Temperament, their number and 
strength is sooner or later perfit- 
ted, and accordingly causes either 
Quotidians, Tertians, or Quartans, 
&c. 
In order therefore to establish a 
probable and likely Hypothesis of 
the causes of Continual and Inter- 
mitting Feavers, I think it not 
amiss to joyn the two suppositions 
of these celebrated Authors toge- 
ther, and make one of ’em; in ad- 
mitting what Sylvius advances of 
Continual Feavers, and Willis of 
the Intermitting; but lopping off 
what the former asserts of the In- 
termitting,

(90)
termitting, and the latter of the 
Continual. This Hypothesis has 
been largely enough explain’d, and 
needs no other confirmation than 
that all the Phenomena and Symp- 
toms that attend both Continual 
and Intermitting Feavers are more 
easily explicable by it than any 
other; for as to the continuation 
of Feavers, ’tis certain that the 
Bile which at all times makes up 
a part of the Mass of the Blood, 
and the Lymphe which is conti- 
nually emptyed out of the Glan- 
dules into it, must needs raise a 
feaverish and violent Fermentation, 
when either or both of ’em is de- 
prav’d (that is, when the Lym- 
phe becomes more Acid than Na- 
turally it is wont to be, or the Bile 
more sharp and lixivious;) and 
this Fermentation cannot choose 
but be continual, by reason of the 
continual presence of its cause, viz. 
The mutual concourse of the Bile
and 


(91)
and Lymphe; which when meek 
and agreeable is acknowledg’d by 
all Judicious Physicians to be the 
cause of the natural and healthy 
Fermentations of the Humors; and 
consequently they are justly entitled 
the cause of the Preternatural, when 
they transgress the bounds of their 
natural Temperaments. 
In like manner the Remissions of 
Intermitting Feavers are plainly 
deducible from Willis’s Supposition 
of the crude parts of the Chyle 
that require a set-time for their 
exaltation and encrease of their 
quantity; which set-time is varia- 
ble, as the Chyle is variously de- 
prav’d, and its conversion into Blood 
vitiated; and as the Blood it self 
is variously disturb’d and perverted 
in its Constitution: Just as the va- 
riety of Continual Feavers takes 
its rise from the various Exaltati- 
on and Depravation of the peccant 
Lymphe or Bile, and from the 
great-


(92)
greater and lesser Corruption or 
Putrefaction of the Blood. More- 
over, this Doctrine of the Inter- 
mitting Feavers is confirm‘d by 
many other reasons mention’d in 
Willis; as first that they are for the 
most part cur‘d by fasting and absti- 
nence from Food; that they are ac- 
celerated and their Paroxysms ren- 
der‘d more frequent, by the Errors 
of Diet, and too frequent Eating; 
whereas they become slower and 
their Fits more unfrequent, by a 
spare Diet, and short Commons. And 
besides (which is very remarkable) 
that their Cure is oft-times better 
performed by Vomiting than any 
other remedies: All which Consi- 
derations do forcibly evince that 
the cause of these Feavers must be 
seated in the chamber of the first 
concoction, and can be no other than 
the nutritive juice. 
But when we agree with Sylvius 
in deducing Continual Feavers from 
the

(93)
the concourse of the lymphe and bile, 
which being Heterogeneous when 
incorporated with the Blood are the 
fittest Principles for raising a Fer- 
mentative Motion, we only under- 
stand it of the Continual Feavers 
that are Essential, and Originally 
Rise from the Blood; for the Symp- 
tomatick Feavers that attend Infla- 
mations or Ulcers, have evident e- 
nough causes of their own, which 
are the Miasms or corrupted Particles 
that are convey'd to the Blood as it 
circulates through the Inflame'd or 
Ulcerated Part; and being Heteroge- 
neous and for the most part endou'd 
with a violent motion, dispose the 
Blood for undergoing a preternatu- 
ral Fermentation. 
Having premis'd so much of Con- 
tinual and Intermitting Feavers in 
General, we come in the next place 
to treat of their numerous progeny; 
of particular Feavers; and to exa- 
mine if their Symptoms accord with
the 

(94)
the alledg’d Hypothesis. And to be- 
gin with the Simple Continuals, An 
Ephemera or Day-feaver seems to 
take its rise from the Bile, shar- 
pen’d and exalted a little above its 
natural State, by several Procatar- 
ctick Causes, such as the heat of the 
Sun, drinking of Wine, Labour, &c. 
which cannot raise any lasting or 
violent Fermentation, but being 
mix’d with the Lymphe may pro- 
duce a short and easy commotion 
in the Blood, but cannot entail 
upon it any great Putridity, or 
Dissolution of its constituent Prin- 
ciples. 
In Putrid Feavers both the Bile 
and Lymphe are much more de- 
prav’d than in an Ephemera, the 
measure and degree of their exal- 
tation being much greater, so that 
a greater and longer Fermentation 
of the Humors must needs ensue, 
which dissolves the band of its Prin- 
ciples, and causes a Putrefaction in 
the whole Mass of the Blood.
A 

(95)
A slow lingring Feaver proceeds 
from the same causes when more 
unactive and dull; and besides, from 
the Blood exhausted of its Spirits 
and Volatile Sulphur; for ’tis by 
reason of their deficiency that the  
Effervescency (tho’ preternatural) is 
so remiss and faint. 
An Essential Hectick differs little 
or nothing from the last mention’d, 
and therefore is generated by the 
same cause: But a Symptomatical 
Hectick that accompanies internal 
Ulcers, proceeds from the putrified 
Heterogeneous Particles that are 
continually transmitted from them 
to the Mass of the Blood; but be- 
ing not very numerous, create but 
a gentle and soft Effervescency. 
A Malignant Feaver proceeds 
from the sharpest and most lixivi- 
ous Bile, or from some sharp cor- 
puscules imbibed from the Air, or 
receiv’d by infection, and convey- 
ed to the Blood, in which they
exalt 

(96)
exalt and sower or sharpen the Bile, 
so that the Blood is sensibly dis- 
solv’d and totally corrupted, whence 
ensue those grievous Symptoms, 
that are peculiar and appropriated 
to this kind of Feavers. 
The Pestilential is a degree higher 
than a Malignant, proceeding from 
the same Causes, but more intense, 
and consequently is attended by 
the like but more dangerous Symp- 
toms. 
A Causon or Burning Feaver is 
owing to the oily and sharp Con- 
stitution of the Bile, which enclines 
it to a violent Effervescency with 
a Viscid and Acid Lymphe; whence 
proceed the burning Heat and un- 
quenchable Thirst; for the Parti- 
cles of the Blood being grosser, 
and being once stir’d up to a Fea- 
verish motion, must of necessity 
make a deeper Impression, and 
create a more intense Heat. 
A

(97)
A Lipyry derives its Original from 
an oyly and sharp bile, joyn’d to an 
Acid but thin lymphe; whence 
it comes to pass that while an in- 
tense Fermentation is caus’d in the 
greater Vessels, the Capillary extre- 
mities or habit of the Body are pos- 
sess’d with a sense of cold, by rea- 
son of the tickling and nipping of 
the Acid and thin lymphe, that be- 
cause of its thinness fly’s out, and 
repairs to the Membranous parts, 
viz. The fleshy skin, or the com- 
mon Membrane of the Muscles; and 
causes the effect above mention’d. 
But if a Lipyry be Symptomatical, 
or such a one as follows the inflam- 
mations of the Ventricle, Middrif, 
and Breast, ’tis to be ascrib’d to these 
corrupted particles that issue from 
the inflamed part, and are communi- 
cated to the blood to which they are 
Heterogeneous, whence ensues a fea- 
verish Fermentation in the larger 
Vessels, and centring about the in- 
F ternal

(98)
ternal parts affected, while the ex- 
ternal are not so much oppressed 
with heat, either because they are 
distant from the Seat of Inflamation, 
or because the Motion of the Hu- 
mors is remisser than in other cases; 
or an Acidity prevails in the Lym- 
phe; or else because the Inflamation 
being internal is likewise Communi-  
cated to the Heart, so that its constri- 
ction or Systole not being duely or 
regularly perform’d,the Blood is not 
diffus’d through the external parts so  
as to heat them. 
The Causes of the Epiala, and Hor- 
rifick, are much of the same Nature; 
but with this peculiar difference that 
in them the Acid Lymphe, pre- 
vails o’re the Oyly sharp Choler, so 
that when the Blood circulates 
round the parts, the Continual or 
Frequent Separation of the Acid 
Lymphe, occasions either a mix’d 
sense of cold and Heat, or Frequent 
Shiverings.
The

(99)
The Elodes or Sweating Feaver 
is caus’d by the choler when it is 
more sharp than oily; by vertue 
of which the Blood abounds with 
Serosities, that are Evacuated thro’ 
the Glandules of the Skin, being 
separated by the feaverish heat. 
The Worm-feaver comes from 
the putrid Miasms that proceed 
from the Guts, where the Worms 
are engendred, and thence conveyed 
to the Blood through the vasa lactea, 
or Milky Vessels. 
The Swoonding Feaver is pro- 
duc’d by the same cause as the Ma- 
lignant; for the Blood being totally 
deprav’d and corrupted, cannot af- 
ford such elastick matter as the 
heart requires, nor furnish the 
brain with matter fit to beget Spi- 
rits. 
Thus may we easily deduce the 
causes of all the other particular 
simple Feavers, whose differences 
tho’ not very remarkable are only
F2 taken

(100)
taken from the various accidents 
and symptoms that are wont to 
attend them, such as Vomiting, Ra- 
ving, Convulsions, and all others 
that may ensue upon the Transla- 
tion of the Morbifick matter into 
the Ventricle, Head and Muscles, by 
reason of the Corruption of the 
Choler or Lymphe; or (which is 
most of all to be taken notice of 
in all kinds of Feaver) from the 
various temperament and dispositi- 
on of the Blood, arising from the 
different union and exaltation of its 
Principles, which may be diversi- 
fied so as to produce many diffe- 
rent sorts of Feavers. 
As to the Intermitting Feavers 
which with Willis we have ascrib’d 
to the depravation of the Nutritive 
Juice and the Blood, the difference 
of the Quotidan, Tertian, Quar- 
tan (both simple and triple) Er- 
ratick and Subintrans is merely ac- 
cidental. For all Intermittents of
what 

(101)
what nature soever are but one 
sort or species of Feavers; arising 
from the greater or lesser corrup- 
tion of the Chyle or Blood, in which 
sometimes a lixivious Choler; some- 
times an Acid Lymphe; sometimes 
both together, are exalted, or one 
Principle whether active or passive 
obtains a predominancy over the o- 
ther: All which are much Influenc’d 
by the quicker or slower, the fre- 
quent or unfrequent approach of 
plentiful or scanty quantities of 
such Particles of the Chyle as are 
not subdued by the Blood, but 
stand out like Heterogeneous Bo- 
dies, gathering more force by the 
accession of fresh recruits; and by 
reason of the variety both of quan- 
tity and quality in these Particles, 
do cause an Irregularity in the Pa- 
roxysms, which are sometimes short- 
er, sometimes longer; sometimes 
return very speedily, and some- 
times observe larger Intervals. And
F3 are 

(102)
are sometimes Anticipated, some- 
times Retarded by the different use 
of the fix non natural things. But 
withal it may guess’d that in the 
Quartans, Quintans, and Sextans, 
the Morbifick Cause or Feaverish 
Ferment is grosser, duller, and more 
entangled; whereas it is more 
active, thin, and disengaged in the 
Quotidians, Tertians, and all such 
Feavers as have frequent and short 
Paroxysms: Or, to express my self 
more clearly, that an Acid Lym- 
phe which imparts to the Blood an 
acid or austere disposition, is peccant, 
and predominant, in all such Inter- 
mitting Feavers as have unfrequent 
Paroxysms that return not before 
the fourth, fifth, or sixth day: But 
that a sharp and exalted Choler 
reigns in those whose Paroxysms 
recurr frequently. Which Suppo- 
sition is confirm’d by Experience, 
for we see that those who are of a 
Melancholick Temperament, whose 
Blood


(103)
Blood is Acid, Gross, or Austere, 
are more liable to Quartans and 
Quintans, than those of a Cholerick 
Sharp Disposition, who are more 
apt to be troubled with Quotidians, 
Tertians, or Feavers that have fre- 
quent and short Fits: besides, the 
slowness and inactivity of the Fer- 
ment in Quartan, and Quintan Fea- 
vers, more than in the Quotidian 
and Tertians, is sufficiently evi- 
denc’d by the duration of the Pa- 
roxysms which in the former ex- 
ceeds that of the latter; for the 
gross resisting Blood, and their dull 
unactive ferment require longer 
time for compassing the end of the 
Feaver. 
But While we are discoursing of 
the Paroxysms of Intermitting Fea- 
vers; ’tis worth our while to ob- 
serve, that they do not only differ 
in their number, frequency, and 
period of returning; but in the 
quality of the Humor to be expell’d;
F4 for
 


(104)
for sometimes, after both the cold 
and hot Fit there follows no sweat; 
sometimes the heat and sweat take 
both place, tho’ not usher’d in with 
a sense of cold; sometimes the cold 
is very moderate and short-liv’d, 
when the heat is lasting and vio- 
lent, and è contra. But for the 
most part, when the Feaver is 
form’d, the sense of cold siezes the 
patient first, then the heat, and 
afterwards a sweating. The cold 
proceeds from the particles of the 
Chyle, that are not assimilated to 
the Blood, but are very Acid, and 
being Accumulated in it circulate 
along with it through the mem- 
branous parts of the Body, and the 
common musculary membrane, 
where being agitated by the grow- 
ing Turgescency of the Blood, they 
fix themselves like so many wedges: 
And from the sower, sharp or acid 
Particles of the Blood, that accord- 
ing to its various disposition desert
the 


(105)
the rest of its Mass at the extre- 
mities of the Capillary Vessels, by 
vertue of the beginning Efferves- 
cency, and there stimulate or velli- 
cate the sensible parts, causing a 
sense of cold, which either conti- 
nues or ceases, or is interrupted, as 
the parts of the Chyle are either 
free or engaged; or variously dis- 
pos’d in their quantity or inequali- 
ty, or as the Blood it self is variously 
temper’d. The Heat that succeeds 
to the Cold is owing to an extra- 
ordinary violent agitation of the 
constituent particles of the Blood, 
which necessarily diffuses a heat 
over all the parts of the body; for 
tho’ Experience proves that there 
may be fermentative motions with- 
out heat, as in the dissolution of 
Corals; yet that can never come 
to pass in the fermentation of a 
sulphureous fat Liquor, such as the 
Blood: Or, as we have already re- 
mark’d in the beginning of this
F5 Trea-

(106)
Treatise, the heat may proceed from 
the prevalency of the Choler above 
the Lymphe; in like manner as the 
cold was said to arise from the 
predominancy of the Crude and 
Acid Particles of the Blood or 
Chyle above the sulphureous bili- 
ous parts. The sweating likewise 
is caus‘d by the commotion of the 
parts of the Blood, which facili- 
tates the separation of the Serum 
in the Glandules under the Skin 
(its proper receptacles) as is evi- 
dent by the influence of the heat 
of Summer, and violent Exercises; 
and also by the quality of the Blood 
which being melted and dissolv’d 
by the internal Effervescency is 
better dispos’d for the dismission 
of its Serum, which finds an easy 
and patent egress, by reason that 
the pores of the Skin are dilated 
and enlarged by the heat. This 
sweat puts an end to the Paroxysm,  
by reason that the Crude Hetero-
geneous 


(107)
geneous Particles of the Chyle are 
subdu’d and reduc’d into order by 
the agitation and commotion of 
the Blood; and thus the whole 
Mass of the Blood acquires a new 
Configuration and Disposition of 
parts; and so prevents the irregular 
and immoderate entrance of the 
subtile matter which was wont to 
disturb it: Or else because these He- 
terogeneous Particles are precipita- 
ted and convey‘d to their proper re- 
ceptacles; which being separated 
from the Blood, the feaverish mo- 
tion must needs cease. But this 
sweat as well as the cold and heat, 
that make way for it, is very dif- 
ferently Circumstantiated; some- 
times when the Blood is less dis- 
solv‘d, or the viscidity of the Lym- 
phe hinders the separation of the 
Serous humor, there ensues no 
sweat at all: At least, it is of longer 
or shorter duration, and more or 
less copious, as the causes which
make 

(108)
make way for it, are more intense 
or remiss, and more active or dull 
in exerting their strength. What 
has been said of sweating is equally 
applicable to the cold and heat 
which are either quite absent, or 
alter’d in length and shortness of 
duration, as their above-menti- 
on‘d causes are more or less ex- 
alted. 
Having now in some measure 
explain’d the Causes of simple con- 
tinual and intermitting Feavers, 
it were seasonable in the next 
place to proceed to the causes of 
Compound Feavers; but, as we 
observ’d above, Compound Feavers 
(that is such as are continual and 
withal have remission and periodi- 
cal Fits) are a mixture of Conti- 
nual and Intermitting ones; and 
therefore we choose rather to su- 
persede the relation of their causes, 
which are no other than the Bile 
and Lymphe vitiated on one side,
inducing 

(109)
inducing the Heterogeneity into 
the Mass of the Blood, that causes 
the continuation of the Feaver; 
on the other side the Nutritive 
Juice degenerated and deprav’d, 
or Heterogeneous and disproporti- 
on’d to the Blood into which it 
runs; whose crude and unconcoct- 
ed Particles are after a certain pre- 
fix’d measure of time accumulated 
and heap’d up in the Mass of the 
Blood, so as to cause a feaverish 
Paroxysm, which is of shorter or 
longer duration, and returns soon- 
er or later, or is accompany’d with 
grievous or meek Symptoms, as 
the Heterogeneity in the Blood is 
greater or lesser, as the Chyle is 
more or less deprav’d, and as the 
accumulation and exaltation of its 
crude particles is quickly or slowly 
perform’d. In a word, seeing that 
the causes of their Continuation, 
and also those of their Intermission, 
may be variously exalted or de- 
press’d;

(110)
press’d, when apart; much more 
must their combination or compli- 
cation be infinitely variable, whence 
ensue the infinite numbers and 
kinds of compound Feavers. The 
various Symptoms that are wont to 
attend both Simple, Continual, In- 
termitting and Compound Feavers, 
such as Vomiting, Loosness, Watch- 
ings, Head-aches, Phrensies, Diffi- 
culty of Breathing, Thirst, Con- 
vulsions, Convulsive Motions, &c. 
I purposely omit; by reason that 
this little Treatise which is design’d 
for an Epitome is too narrow for 
such bulky digressions, and (which 
weighs more with me) that they 
are all explain’d and deduc’d from 
their natural causes, in the descripti- 
ons of the other diseases which they 
are wont to accompany. 
As to the Diagnosis or Signs of 
Feavers; a Feaver in general may 
be easily known by the Signs men- 
tion’d in its definition; by the 
heat

(111)
heat which the Effervescency of the 
Blood, and violent motion of its 
Particles diffuses in the Body; by 
the acceleration of the pulse occa- 
sion’d by the frequent contraction 
of the Heart, for the animal Spirits 
are render’d more moveable and ac- 
tive by the feaverish heat, & so more 
dispos‘d for the frequent contracti- 
on: And the Blood having its Prin- 
ciples exalted by the heat furnishes 
the Elastick and Explosive matter 
for accelerating the Heart’s moti- 
on, more readily and copiously 
than at other times. If the pulse 
at any time be weak or low, it 
proceeds from a lesser contraction 
of the Heart, which do’s not ex- 
pel the Blood totally into the ar- 
teries, by reason of the deficiency 
or dissipation of the Spirits, or 
else the deprav’dness of the Blood 
that cannot afford the necessary 
Copula or cement to its parts. But 
if the Elastick parts of the Blood be
not 


(112)
not deprav‘d nor consum‘d, and 
the Spirits neither exhausted nor 
their motion empair‘d, then is the 
pulse full, strong, and high. And 
hence we may observe that in the 
beginning of almost all Feavers, 
the pulse is strong and full, but 
as the disease advances becomes 
small and weak; I said, almost, be- 
cause it may sometimes happen 
that the Blood tho’ highly Putrified 
and Corrupted may abound in the 
Body and distend the Arteries and 
Veins when it conceives an Efferves- 
cency, and therefore requires more 
room; and consequently may in- 
duce a low and weak pulse, by 
reason that when ’tis receiv‘d in- 
to the Ventricles of the heart, the 
contraction of the heart cannot 
deposite it all into the Vessels, the 
Blood that came first out being 
sufficient to fill ’em; so that there 
remains some share of it in the Ca- 
vities of the Heart, that resists and 
lessens


(113)
lessens the contractive motion; 
which causes a lesser elevation of the 
Arteries; and in this case, the low- 
ness of pulse signifies only an oppres- 
sion of the strength, not a total decay 
which proceeds from deficiency of 
Spirits and the poverty of the Blood. 
The Signs of the Essential, Symp- 
tomatical, Simple, Continual, Inter- 
mitting and Compound Feavers may 
easily be gather‘d from what we 
have said of ’em in recounting their 
general divisions. But a Continual 
not Putrid, or a simple and extended 
Ephemera or Synochus may be di- 
stinguish’d from the rest by the 
measure of its duration which is 
but for a day or two, and by the 
presence of the Procatarctick Cau- 
ses that for most part give it a 
being; Secondly, from the meekness 
and moderation of the Heat, and 
remissness of the Symptoms; and 
thirdly, by this quality, that it admits 
no Exasperation, begins with little
or 


(114)
or no shivering, and is for the most 
part terminated by a gentle Swear. 
A Continual Putrid may be 
known by the duration which ex- 
tends to several days, and some- 
times weeks; by the sharp and vi- 
olent heat that proceeds from the 
greater Agitation and Effervescen- 
cy of the Particles of the Blood, 
which unlocks the bands of its Prin- 
ciples; and lastly by the Shivering 
with which it begins, and the other 
grievous Symptoms, such as Nause- 
ousness, Vomiting, Head-aches, 
Phrensies, Immoderate Watchings, 
Blackness and Dryness of the 
Tongue, and an Unquenchable 
Thirst, &c. An Acute Continual is 
known by the feverity and num- 
ber of its Symptoms, the heighth 
of its Heat, the shorter duration of 
the Feaver, and by the Pulse which 
is strong, but withal quick. A 
Chronical or Hectick (for these two 
are much allied to one another)
is 

(115)
is known by the length of the 
Feaver, which reaches sometimes 
to some Months; Secondly by the 
gradual and successive encrease of 
the Symptoms; Thirdly by the 
remissness of the heat, which is 
augmented some hours after eating, 
by reason of the concourse of the 
Chyle with the Blood; Fourthly 
by the weakness and lowness of 
the Pulse; and lastly by a Con- 
sumption and Decay that gradually 
creep in upon the whole Body. 
The Signs of a Malignant Feaver 
are, a sensible dissolution in the 
Blood when let forth from the 
Veins; fluxes of blood that cannot 
be stopp’d; pustles and spots 
breaking out in the Skin, frequent 
syncope’s or swoondings, the body 
less hot, a stubborn and consuming 
Loosness, Vomitings, Hickups, 
Convulsions, Delirium's, and a weak 
small Pulse. A Pestilential is 
known by the Contagion, the fre-
quent 

(116)
quent numbers of Sick People, and 
their frequent Death; by Buboes, 
Carbuncles, and the many other 
grievous Symptoms that usually 
attend it; it is likewise known by 
its being Epidemical, or arising 
from a common cause, such as bad 
Food or corrupted Air. The lesser 
differences of Continual Putrid 
Feavers may be easily understood 
from what has been said already, 
and from the respective Diseases 
and Symptoms they are joyn’d 
with. 
The Compound Feavers, such 
as a Continual Quotidian, Conti- 
nual Quartan, Semitertian, &c. 
are known by the Continuation 
attended with periodical Fits. 
The signs of Intermitting Fea- 
vers are not only a shivering, heat 
and sweating mutually succeeding 
one another, but also the Apyrexia 
or absence of the Feaver after the 
Fit is over. We may discern by
the 

(117)
the regular or irregular returning 
of the Fits if the Feaver be orderly 
or disorderly; and by the set pe- 
riod for the return whether it be 
a Quotidian, Tertian, Quartan or 
Quintan; and from their return 
oftner than once every day, or 
next day, or third day, may we 
judge if it be a double or treble 
Tertian, or Quartan; for, as we 
have said already, Intermitting Fea- 
vers are denominated from the 
time and manner of the Paroxysm’s 
return. The Symptomatical that 
is not originally seated in the Blood, 
but is an Appendix or Consequent 
of another Disease, is so easie to 
be known that it needs no Signs; 
and its particular differences may 
sufficiently appear from the pre- 
sence of an inflammation, Erysi- 
pelas, Imposthume, Ulcer, Gan- 
grene, &c. 
The Prognosis or Judgment of 
Feavers is as various as their spe- 
cies

(118)
cies or kinds are. The Ephemera 
is the least dangerous of ’em all, 
by reason of the lesser Putrefaction 
of the Humors that it signifies. 
The Putrid is much more dange- 
rous, and is to be more or less 
suspected, with respect to the great- 
ness and number of the Symp- 
toms. A Hectick and Slow Fea- 
ver if they be Essential are Cura- 
ble in the beginning; but when 
they become habitual & confirm’d, 
or when they are Symptomatical 
depending upon Ulcers of the In- 
ternal parts, they fall not within 
the Verge of a Cure. An Acute  
Feaver, a Burning Feaver, Swoon- 
ing, Sweating, Lipyry and Con- 
vulsive, do always bode an ill event. 
A Milk Feaver, Arthritick, Rheu- 
matick, Worm and Catarrhous Fea-  
vers, are not accounted so danger- 
ous. But the Malignant, Purple, 
and Pestilential are dangerous a- 
bove all, by reason of the extream
Putre- 


(119)
Putrefaction of the Humors and 
Dissolution of the Blood. A Sim- 
ple Continual that admits of no 
encrease or new accession, tho’ it 
be not free’d from all danger, is 
much less to be fear’d than a Com- 
pound that besides its continuation 
is lyable to Exasperations. A 
Symptomatical fore-speaks good or 
evil, as the disease upon which it 
depends is more or less grievous; 
hence we always suspect such as 
slow from an Inflamation of the 
internal or noble parts. Whereas 
such such as slow from the exter- 
nal, as simple Buboes, Erysipelas, or 
Roses, &c. are better accounted of. 
In fine all Acute and Putrid Feavers 
are to esteem’d more or less dan- 
gerous according to their greater or 
lesser train of ill Symptoms, and 
the more or less favourable age, 
temperament, and strength of the 
patient. But if a Feaver be not 
Continual but Intermitting, then
for 

(120)
for the most part it is free of all 
danger: Therefore say’s Hippocra- 
tes, Febres quocunque modo inter- 
miserint pericu'o vacant. I said, 
For the most part; by reason that, 
if the Constitution of the Air or 
the Food be deprav’d, and by 
communicating its Corruption to 
the Blood become the cause of a 
popular Feaver; or if the Feaver 
invade a Cacochymical Body so as 
to endure long, or to suffer fre- 
quent Relapses; in these cases, I 
say, there is good ground for fear, 
and a small prospect of recovery. 
The Quartan and Autumnal are of 
longer duration than the Estival 
and Tertian by reason of the gross, 
stubborn and incorrigible Nature 
of the Morbifick Cause, and the 
Acid Disposition of the Blood, that 
prevails in the Autumn; whereas 
in the Summer the Pores being 
dilated by the heat, the Humors 
are attenuated, and easily dispers’d 
or

(121)
or evacuated. The Subintrant or Er- 
ratick Feavers are more dangerous 
than the Regular; as are all those 
that have longer Paroxysms than 
such as have but short ones. In 
the Paroxysms of all Feavers sweat- 
ing is good, for after Fermentati- 
on the Heterogeneous Particles are 
separated that way from the Blood; 
nay, the frequent observation of 
Physicians attests that in all sorts 
of Feaver sweating (provided it be 
not a cold sweat, nor too copious, 
nor attended with a loss or want 
of strength) is always good; 
insomuch that all Feavers do ge- 
nerally terminate by Sweating. 
The Compound Intermitting Fea- 
vers; that is, the double or triple 
Tertian or Quartan; and all whose 
Fits are attended with grievous 
Symptoms, as a Delirium, Weak- 
Pulse, Thirst, Shortness of Breath, 
Vomiting, Head-ach, &c. are much 
more to be suspected than the
G Simple 

(122)
Simple and such as bring on lighter 
Symptoms. 
As to the Cure of Feavers, the 
scanty limits of this Treatise do not 
allow me more room than what 
may scarce serve for a compendi- 
ous description of the Cure of their 
more general Species. Continual Fea- 
vers, especially the Acute and Ma- 
lignant require frequent Venesecti- 
on, which is to be repeated as often 
as the height of the Distemper and 
strength of the Patient require, 
and that either in the Arm or Leg 
as the various indications are: 
Also Refrigerating and Acid Me- 
dicaments; which serve to mode- 
rate the heat of the Blood; such as 
all the cooling Herbs, Roots, Seeds, 
and destill’d Waters, all the Acid 
Spirits and Juices mention’d by 
us elsewhere, of which may be 
made Broaths, Juleps, Emulsions, 
&c. The Refrigerating and Purg- 
ing Clysters are very convenient,
and

(123)
and purging Draughts given at 
seasonable times, which are made 
of cooling Decoctions, with the 
addition of Tamarinds, Senna, 
Cassia, Manna, the Solutive Sy- 
rup of Roses, and Powder of the 
Roots of Jalap, if strong pur- 
gation be requisite. An Ephe- 
mera and not Putrid either termi- 
nates of its own accord, or is cur’d 
by one or two Venesections, and 
the short use of some other simple 
remedy. 
But a Putrid, whether Inter- 
mitting or not, requires greater 
store of Medicines, and a longer 
usage of ’em. And ’tis to be re- 
mark’d that in this and all other 
kinds of Feavers the variety of the 
Symptoms occasions great variety of 
Prescriptions For when they are at- 
tended by frequent Watchings. Deli- 
riums, Convulsions, or Phrensies, we 
presently give Narcoticks, and let 
G2 Blood

(124)
Blood from the Saphena: If by Vo- 
mitings, we first take care to eva- 
cuate the deprav’d Humors that 
caus’d ’em, and then prescribe Lau- 
danum, or the Acid Remedies 
that are fit for putting a stop to 
Vomiting. If a Loosness, especi- 
ally if Symptomatical, Colliqua- 
tive, or Inveterate, we first give 
Anodynous Clysters, then Deter- 
gents, and last of all Astringents. 
If the Humor be translated to the 
head, and produce a Sleepy Distem- 
per, we first let Blood in the 
Ancle, and then administer Vi- 
num Emeticum, provided the 
strength of the patient be suf- 
ficient to bear it. If there appear 
any obstruction in the Bowels, and 
distention of the Hypochondria or 
lateral parts of the Belly; Clysters 
are frequently to be Administred, 
and withal such as Purge Violent- 
ly, together with Emollient Fo- 
mentations. The like variety is
to 

(125)
to be seen in all other Symptoms. 
A Burning Feaver, by reason of 
its intense heat, requires more 
frequent and copious bleeding, 
and larger quantities of cooling and 
acid Remedies, besides the univer- 
sal Remedies that are equally ne- 
cessary in all Feavers. 
A Syncopal or Swooning Feaver 
calls for Spirituous and Strengthen- 
ing Remedies, but in moderate 
quantities, left the Feaver be more 
exalted. 
An Elodes or Sweating Feaver 
is cur’d by such Cooling and Acid 
Remedies as hinder the Dissolution 
and Colliquation of the Blood. 
A Malignant, Purple, and Pe- 
stilential Feaver (which are all 
near a-kin to one another, and con- 
sist in an extream Dissolution and 
Corruption of the Blood) do cer- 
tainly require bleeding, whatever 
the Ancients may say to the con- 
trary, who falsly Imagin’d that 
G3 Blood-

(126)
Blood-letting drew the Malignity 
or Poyson from the habit of the 
Body to the Center; and who 
were wont to Administer Alexi- 
pharmaca or Cordial Remedies 
which serv’d only to augment the 
Dissolution of the Blood; instead 
of which we choose rather to give 
Cooling and Acid Medicines, 
which correct the said Dissolution; 
tho’ in the mean while the Uni- 
versal, General, Remedies ought 
not to be neglected 
All the other Symptomatical 
Feavers, such as the Rheumatick, 
Dysenterick, Catarrhous, Worm- 
feavers, and all that proceed from 
Inflamations, together with the 
Slow-feavers that follow upon Ul- 
cers of the internal parts, require 
no other method of Cure than what 
has been already mention’d in the 
Descriptions of Rheumatisms, Loos- 
nesses, Catarrhs, Worms, Pleuresies, 
Gouts, Inflammations of the Liver
or 

(127)
or Ventricle, Consumptions, and In- 
ternal Ulcers. 
Hectick Slow Feavers, while 
they are Essential, are only Cura- 
ble by Alterative and Moist Reme- 
des; so that neither letting of 
Blood, nor violent Purgations can 
take place in it; but Clysters, and 
Gentle Purgers are very convenient. 
Bathing in sweet Water is very 
good, tho’ in all other Feavers, 
especially Continual and Acute 
ones, it be highly Pernicious, be- 
cause it stops the Transpiration and 
stifles the Steams, and thus en- 
creases the Feaverish Heat. Whey, 
Cows and Asses Milk are very good 
if moderately us’d; but large quan- 
tities of ’em are hard to be digest- 
ed. Strengthening and Restorative 
Food is very useful, such as 
strong Broaths, Gellyes, and Nou- 
rishing Meats, with the addition 
of Spirituous and Volatile Reme- 
dies, but in very small Doses. If
G4 the 

(128)
the Slow-feaver be encourag’d or 
cherish’d by any obstruction in the 
Bowels which hinders a due sepa- 
ration of the Recrements from the 
Blood, then unto the above menti- 
on'd Remedies we ought to add 
the temperate Aperients, and with- 
al forget net to use Emollient Fo- 
mentations. 
As to the Epialœ, Lipyriæ, Hor- 
rifick, or such like Feavers as are 
attended by Shiverings, Horrour, 
or sense of cold; for so much as a 
certain measure of Acidity prevails 
if them; after having let Blood 
in a sufficient quantity and pre- 
mis'd the other General Remedies, 
it shall not be improper to admi- 
nister Diaphoreticks, especially such 
of ’em as are of thin and subtil 
parts, for the other sorts of Sudo- 
rificks raise but a small commotion 
in the Blood, which we ought 
sometimes to augment when the 
Fermentation is Lauguid, or when
Blood 

(129)
Blood has been frequently let. Nay, 
there are many Physicians who 
think that since Feavers do natu- 
rally terminate in sweating, Dia- 
phoreticks of all sorts must needs be 
convenient in all sorts of Feavers, 
because that Quo natura ducit, eo 
ducendum. But tho’ Sudorifick or 
Sweating Medicines may be sus- 
pected in Acute Feavers, because 
they exalt the Fermentation of 
the Humors, which is high enough 
of it self; yet when they are pru- 
dently and judiciously Administred 
they contribute much to the Evacu- 
ation of the Morbifick Cause; for 
by raising a sweat they extract and 
disengage the Salts that are dis- 
solv’d in the Serum of the Blood, 
which make up a great part if not 
the whole of the Morbifick Cause. 
But we ought to take strict notice 
that the Effervescency of the Hu- 
mors be not very violent, and that 
the Vessels be unloaded by letting 
Blood

(130)
Blood, before we give ’em; and 
hence the most Celebrated Practiti- 
oners observe this method of Admi- 
nistring Sudorificks, as the Powder 
of Vipers, and the like, in the 
Measles, Small-Pox, Purple, Pete- 
chial, and Malignant Feavers, in 
which Nature endeavours to throw 
out the Heterogeneous Particles up- 
on the skin or habit of the Body; 
tho’ in the mean time they are sen- 
sible of the Poverty and Dissolution 
of the Blood, and that these Medi- 
caments tend to augment its Disso- 
lution. For they consider that all 
that disadvantage is more than re- 
compenc’d by the benefit it do’s to 
Nature, in assisting it to expel the 
Heterogeneous Particles, and thus 
retrieving to the Blood its Ancient 
and Natural Diathesis. 
Besides what has been said of the 
Cure of Feavers, the following di- 
rections are to be carefully observ’d; 
first that in a Malgnant Feaver, 
when

(131)
when the Blood is altogether dis- 
solv’d we ought not to use Scarified 
Cupping-glasses, lest the Blood be- 
coming all over fluid should repair 
to the Scarified place with so migh- 
ty a current, as would not be easily 
stop’d; secondly, that the more A- 
cute the Feaver be, the more slen- 
der and thin must be their Diet. 
Thirdly, that Bleeding is only 
seasonable in the beginning while 
the Effervescency is yet Vigorous; 
but Purgation, when the Feaver de- 
clines, and the Fermentation abates. 
Fourthly, that when the Pulse is 
weak, or low, or intermitting, Di- 
aphoretick and Cordial Remedies are 
more proper than Narcoticks. And 
lastly, that the frequent use of some- 
times Cooling, sometimes Purging 
Clysters is very convenient in all 
sorts of Feavers, for they insensibly 
evacuate the greatest quantity of 
the morbifick matter, and cleanse 
the first ways that furnish the Blood 
with deprav’d Humors.
It 

(132)
It remains now that we should 
conclude this Treatise with the Cure 
of Intermitting Feavers, which tho’ 
it be not exactly the same with that 
of the Continual, vary’s not much 
from it; for the same is the cause of 
both, and differs only in its greater 
or lesser abundance or exaltation. 
And in the first place, as to the ge- 
neral Remedies; Venesection if fre- 
quently repeated do’s more harm 
than good; tho’ in the mean time a 
Physician that weighs with judg- 
ment the Temperament, Age and 
Constitution of the patient may 
venture in some cases to Prescribe 
the Repetition of it. Purgatives 
seem more proper for cleansing the 
first ways, that are always faulty; 
for fevering the heterogeneous parts 
from the Blood, and correcting its 
perverse Constitution. But Strong 
Emeticks, if the strength will al- 
low, are more profitable in the be- 
ginning than Purgatives. Purging 
Clysters

(133)
Clysters are to be frequently Admi- 
nistred both in Intermitting and 
Continual Feavers. Alteratives are 
more effectual than the Evacuating 
Remedies, especially those of ’em 
that are bitter, and therefore call’d 
Febrifuga such as Wormwood, Ger- 
mander, and lesser Centaury boil'd 
in Water; also their Salts, and all 
Volatile, Fix’d and Sudorifick Me- 
dicaments. The Powder of Kinkina 
or its infusion in Water or White- 
wine is a celebrated Remedy; a 
Dram or two of Triacle given in the 
Decoction of Succory is very suc- 
cessful. Fasting and abstaining from 
food is much commended. The fol- 
lowing Ptisan is exceeding good. 
Take of the Leaves of Senna ℥ ß. 
Centaury the lesser. p ij. Salt of Worm- 
wood ʒ iß. boil them in Spring- 
water ll 1. of which the patient may 
take two or three Ounces every 
Morning; and in the very heat of 
the Paroxysm. All these and many 
other

(134)
other Remedies for brevity’s sake 
here omitted are call’d Specifick or 
Febrifuga, because they containing 
within them a Saline Sulphur, or 
Lixivious Salt, are fittest for cor- 
recting the Acidity of the Lymphe, 
and Redundancy of Crude Chylous 
Particles in the Blood; or for re- 
moving the Heterogeneity of Parts 
that opens a door to the ethereal 
matter, which causes the agitation 
or commotion of the Blood. But in 
the mean time, for so much as in all 
Intermitting Feavers the first con- 
coction is vitiated, it shall not be a- 
miss after the administring of Vo- 
mits, to prescribe strengthening and 
digesting remedies; and if any other 
Symptoms accompany the Feavers, 
such as Immoderate Watchings, De- 
lirium's, Vomiting, Sleepy Distem- 
pers, &c. they are to be remov'd by 
their proper and peculiar Remedies 
mention’d in their proper places; 
but with this caution, that all cool-
ing

(135)
ing and acid things are to be 
shun’d, because they augment the 
Feaver. But if an Intermitting Fea- 
ver be cherish’d by an obstruction 
in the Bowels, we ought to mix ape- 
rients with the above mention’d 
Remedies; which method is for the 
most part attended with success. 
I supersede any further descripti- 
on of Intermitting Feavers, having 
already compass’d my design, which 
was to give a general scheme of all 
Feavers, and their proper cures; 
and therefore shall purposely omit 
that long train of Specifick Medi- 
cines that other Authors have stuff'd 
their Books with. 
As to the Continual compounded 
Feavers, which besides their conti- 
nuation are subject to Fits; Practi- 
tioners are wont to cure them by 
the same Remedies as are prescrib'd 
in simple Continual Feavers, unto 
which they add the Powder of Kin- 
kina given in Succory or Poppy Wa- 
ter;

(136)
ter; and with very good success. 
N. B. 1. that ʒ ij. or the Powder of 
Kinkina maybe administred in Suc- 
cory or Purslain Water in Continu- 
al Feavers; but in the Intermitting, 
in White-wine; about two or three 
hours before the accession of the Pa- 
roxysm. 
2. That if the patient be weak or 
tender we ought to attempt nothing 
during the Paroxysm; but in robust, 
strong Constitutions letting Blood 
and Purging may not be amiss. 
3. That in Intermitting Feavers 
we give ʒ ij. of Powder of Kinkina 
the first day, the next Morning ʒ j. 
and as much at night, for the more 
effectual fixation of the Morbifick 
Cause. 
4. That Attenuating Volatile Su- 
dorificks are most proper in Quar- 
tans and Quintans, whose Paroxysms 
are longer and more unfrequent. 
FINIS.