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No. 11.




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filembic Club ÍReptint2–1 lo. 11
ESSAYS OF JEAN REY
T}OCTOR OF MEDICINE
ON AN ENOUIRY INTO THE CAUSE WHERE-
FORE TIN AND LEAD INCREASE IN
WEIGHT ON CALCINATION
(1630)
*
EDINBURGH
THE ALEMBIC CLUB
, CHICAGO
THE UNIVERSITY OF CHICAGO PRESS
1902

P R E F A C E.
HE title of the work which has here been translated
is “ Fºssays de Jean Rey, docteur en medecine, sur la
Aecherche de la cause pour laquelle l’Estain et le Plomb
augmentent de poids quand on les calcine.” It was first
published in pamphlet form at Bazas in 1630, and
reprinted, along with notes and various letters bearing
on the subject, at Paris in 1777. In these Essays Rey
attributed the increase in weight of tin and other metals
on calcination to the action of the air, thus to some
extent anticipating the work of Lavoisier a century and
a half later. He evidently well understood the value
of properly chosen experiments, although he himself
seems to have been little disposed to their perform-
ance, delighting rather in metaphysical speculations
and curiously inadequate trains of reasoning, which yet
lead often enough to just conclusions. Apart altogether
from the historical interest of the work, the quaint and
lively style of the author makes his Essays still worthy
of perusal in the original.
J. W.
l62392
ESSAYS OF JEAN REY,
Doctor of MEDICINE,
ON AN ENOUIRY INTO THE CAUSE
WHEREFORE TIN AND LEAD IN-
CREASE IN WEIGHT ON CALCIN-
ATION.
—º-tºe Pi—4—
PREFACE.
Some eminent personages having observed with aston-
ishment that tin and lead increase in weight when they
are calcined, have been seized with a praiseworthy desire
to enquire into the cause of this phenomenon. It has
proved a goodly subject, but the enquiry has been trouble-
some, and its fruits very small : in so far that after having
directed their thoughts to all quarters, they have only
been able to adduce reasons so feeble that no man of
sound judgment dares trust them for support, or by their
aid shelter his mind from all doubt. The sieur Brun,
Master Apothecary in Bergerac, having lately paid atten-
tion to this augmentation, and believing, as I apprehend,
that no one before him had been aware of it, has invited
me in one of his letters to enter on this line of thought
and furnish him with the cause. Now, since he is a
person whose integrity of life, rare experience in his art,
and other patent virtues, oblige every honest man to wish
him well, I confess that these qualities have had such
6 Rey.
power over my affections, that I cannot deny him this
request. At his prayer, therefore, and friendly solicita-
tion, I have devoted several hours to the question, and
conceiving to have hit the mark I produce from them
these Essays of mine. Not without foreseeing very clearly
that I shall incur at first the accusation of temerity, since
in them I run counter to sundry maxims approved for
many centuries by the majority of philosophers. But
what temerity can there be in exposing the truth to light
of day when one has known it? Might I not more
justly be reputed childishly fearful if I dared not divulge
it, and sordidly envious if I held it concealed? Of the
last two accusations I clear myself, hoping to see myself
freed of the first by all intelligent persons, who, after
having tasted of my reasons, will, if they find them to
their liking, be grateful to me for having set them forth :
and, if they like them not, will not refrain from praising
my efforts to seek the truth in so arduous a question,
and will be incited by my example to treat the matter
more dextrously, to which I invite them. In any case I
shall have testified to the public the desire I have of
Serving it by letting this paper slip from my hands,
although it may be that some hurtful stigma will thereby
be graven on my reputation.
ES S A Y I.
That all things material under the canopy of Heaven
are heavy.
God, in creating the Universe, has made it neither
wholly like himself nor wholly unlike: for, himself being
One, he has made the world as it were not-One, by the
diverse multiplicity of its innumerable parts; willing at
the same time that they should reunite to a certain one-
ness by their exact contiguity. The superior world is
Essays. 7
beyond our subject: the inferior and elementary world
owes this contiguity to the heaviness divinely impressed
in all its parts, assisted by the subtle fluidity of some of
its simple bodies. It is through this quality, with which
the matter of the four elements is more or less invested,
that they are separated from each other and kept each in
his own place, according to the requirements of the
generation of mixtures and the adornment of the uni-
verse. For this matter, filling at every point the space
enclosed beneath the vault of heaven, is continually urged
by its own weight towards the centre. It is true that the
earth as heaviest promptly occupies this place, and forces
his brethren to retreat, so that water, being second in
heaviness, is also second in place: the air then, being
driven from the first and second place, is restricted to the
third, leaving to fire, the least heavy of all, the uppermost
region for his dwelling. Chemists furnish us with an
agreeable representation of this when they take pulverised
black enamel, liquor of tartar, aqua vita coloured bluish
with litmus, and spirit of turpentine reddened with alka-
net; and, casting the whole into a phial, agitate it until a
confused mixture results. The vessel being then left in
repose, the eye perceives with pleasure the process of
disentanglement. The enamel reaches the bottom, re-
presenting to us the earth. The liquor of tartar is its
neighbour, representing water. The aqua vita, resembling
the air, occupies the third place. And the spirit of tur-
pentine, to demonstrate the fire, assumes the highest
position. All this occurs in virtue of heaviness, accord.
ing as it is liberally or sparingly distributed in these
bodies. In the same way the elements can acknowledge
no other cause to arrange and dispose them in their
places, there being no need to introduce the lightness
which our predecessors have vainly excogitated to this
end. * . -
8 Rey.
ESSAY II.
There is nothing light in Nature.
Almost all philosophers, ancient as well as modern,
fearing an eternal confusion of the elements if they were
all endowed with heaviness, have been led to adopt the
belief that the two superior elements are equipped with a
certain lightness whereby they raise themselves upwards
to occupy each his place; and that the two lower ele-
ments are dragged downwards by their own heaviness.
But having in the preceding Essay clearly shown that
there is no need of lightness to effect this, heaviness
alone being sufficient, I embrace the maxim which they
themselves have very prudently put forward, “That we
must never multiply the causes of things without neces-
sity,” and holding as assured that God and Nature do
nothing in vain (as they also teach us), I believe that it
would be otherwise if lightness were admitted, since it is
superfluous. But that is not all. Fire is by nature so
subtle that it scarcely merits the name of substance, and
is consequently denuded of wellnigh all power of resist-
ance, whence it follows that the air mounting upwards
without hindrance would reach the heavens, expelling
the fire from its place, and constraining it to seek a
lower seat, to the detriment of their own doctrine. To
this I add another difficulty, namely, the perpetual and
fruitless strife which would exist betwixt the heavy and
the light elements, the latter pulling upwards and the
former downwards with all their strength. From this
would arise at the place of their contact a state of tension
incomparably greater than that of a cord pulled at both
ends by two powerful hands, imposing upon it such a
strain that rupture is seen to ensue. Such a state is
very far removed from that bond of friendship by which
Nature has sought to join neighbouring elements, em-
Essays. 9
planting in their bosoms similar qualities, by means of
which they communicate amongst themselves and ever
amicably agree together. Whence it results that light-
ness is a vocable which signifies nothing absolute in
nature, so that we must reject it, or, if we retain it, do
so to denote solely a relation of one thing less heavy to
another which is heavier.
ESSAY III.
There is no upward movement that is natural.
What shadows would become if there were no sub-
stance is that which a natural movement upwards becomes
when lightness is abolished. For in truth it would be a
very monstrous thing to see natural effects which had no
cause in Nature. We say that a thing moves naturally
when it has the cause of its movement within itself.
Now casting my eyes on every thing that moves, I find
none that moves upwards of its own motion. It is true
that water rises if we throw earth into the vessel that con-
tains it; but all will admit that this is in virtue of no
lightness residing in itself, but that the earth by falling
down causes the water to rise. If water does not own
lightness as the cause of this upward movement, why
should air do so, taking the same road when water sinks
in it? And why should fire when doing the same P I
doubt not it will be said that, if the upward motion of
the elements be not natural, it must be confessed violent,
whence will follow the absurdity of seeing each of them
keep its station in the universe by violence. To which I
answer that the elements not having in themselves the
cause of such movements, these latter may be said in
that respect to be violent, but theirs is a gentle violence
and in nowise destructive. Thus the motion of the
spheres of the planets from East to West, having its
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IO - Rey.
cause in a higher sphere, is called by us violent, although
it does them no injury. Besides, those who speak thus
will be their own critics, being constrained to admit not
only the violent motion but even the violent rest of
Water and of Air—the latter under the Fire, and the
former above the Earth. Having thus banished lightness
and its upward movement from the whole pale of nature,
let us establish more firmly heaviness in the elements Air
and Fire, which alone are in controversy.
ESSAY IV.
That Air and Fire are heavy, and move naturally
downzwards.
If we had as free commerce with the element Fire as
we have with Air we should not doubtless be so destitute
of experiments to confirm our assertion that those which
we produce with the latter, are conclusive for the former,
in consequence of the proximity of their nature. Now
since we are agreed that all which sinks downwards
without constraint possesses heaviness, whence the move-
ment proceeds, who shall deny this quality to the Air,
Seeing that as soon as we have dragged a stake out of the
ground, it rushes into the hole to fill it? And that we
cannot dig a well so deep that the air does not incon-
tinently move thither, without external force, and without
violence? I will go further: If there were a tube extend-
ing from the centre of the earth far upwards into the
region of fire, open at both ends and filled with the four
elements, each in its ordinary position, then if we with-
drew the earth from beneath, the water would descend
to occupy its place, leaving its own to the air, whose
place would then be occupied by the fire. Then remov-
ing the water from the new position, air would fill it:
and this being also emptied, fire would move thither, and
Essays. I I
fill the whole tube, sinking down to the centre, simply
because what formerly hindered it from so doing had
been removed. Those who will say that this takes place
in order that a vacuum may be avoided, will not say
much : they will indicate the final cause, and we are con-
cerned with the efficient cause, which cannot be a void.
For it is quite certain that in the bounds of nature, a
vacuum, which is nothing, can find no place. There is
no power in nature which from nothing could have made
the universe, and none which could reduce the universe
to nothing: that requires the same virtue. Now the
matter would be otherwise if there could be a vacuum.
For if it could be here, it could also be there: and
being here and there, why not elsewhere? and why not
everywhere? Thus the universe could reach annihilation
by its own forces; but to him alone who could make it,
is due the glory of being able to compass its destruction.
Now if a void cannot exist, how can it cause air and fire
to sink downwards, contrary to their nature? Does not
a real effect ever proceed from a really subsisting cause P
Let us therefore say what is the truth, that it is heaviness
which carries these elements downwards, that it may
unite closely all their particles, and consequently close all
avenues against a vacuum.
ESSAY V.
It is shown that Air and Fire possess heaviness by
the swiftness of motion of heavy things being
greater at the end than at the beginning.
An error, however trivial, committed at the commence-
ment of any discipline, increases as we progress, and most
often involves us in very thorny difficulties. This we
experience in the present subject: for Philosophers having
gone astray almost at the very threshold of natural science,
I 2 Rey.
attributing lightness and a natural upward movement to
the two superior elements, see themselves afterwards
greatly embarrassed to adduce the reason why the natural
downward movement of heavy things is swifter at the end
than at the beginning. The variety of opinions which
we find amongst authors as to this question bears suffi-
cient witness to their perplexity: aiming, as I do, at
brevity, it is not my intention to reproduce them here.
Whoever will, may read a good number in Pererius,
a judicious philosopher, in his book on the natural
Principles, where he reports and learnedly refutes them,
embracing one, to which he protests he will adhere until
he find a better. I will say something of this hereafter
in passing, it being not so much true as plausible. Here
I offer mine, which I have just excogitated in favour
of the truth of the preceding demonstrations. The
swiftness of movement of the heavy body increases from
the beginning to the end by the augmentation of the
elementary matter which weighs down on it, and by the
continual multiplication of the shock it produces on it
in descending. The demonstration will lend clearness to
my statement. Let AA. be the heavens, BB. the earth,
and C. its centre; D. an iron ball descending towards the
earth ; F. the same sunk lower down ; F. still the same at
the middle of its descent, G. the same near the end.
HH. two lines drawn from the centre of the earth to the
heavens, touching the ball D. at the two extremities of
its diameter. II. two other lines drawn in the same
way, touching the ball at E. K.K. two other lines touch-
ing it at F. L.L. two more touching it at G. It is manifest
that the ball when at D., besides having its internal
heaviness, has on it the matter of the elements of air
and fire enclosed between the lines H.H. ; but being at
E. there is then all the matter enclosed between the
lines II., which is seen to be augmented at F. by what
Tessays. I3
the lines KK. contain in addition: and when the ball is
at G., everything contained within the lines L.L. weighs on
it: from which it follows that the speed of the motion
must increase, and be-
sides this there is the
shock which this matter
makes continually as it
sinks on the said ball.
The opinion of Per-
erius has something ap-
proaching this shock:
for he will have it that
the air which follows,
pushes the bullet: but
in this he is mistaken, in
that air being inherently
light and naturally striv-
ing upwards could not
push the bullet down-
wards; any more than a
boat which is hauled
against the current of a
river is pushed up-stream by the water, which, as it meets
the prow, is diverted, and, licking the sides, flows steadily
downwards: for how could it, keeping this direction,
strike the stern upwards? The other part of his statement
is no whit better, for he imagines that the air agitated by
the motion yields more readily to the thing moved. It
is quite the contrary; for air and water when agitated
sustain a greater weight. Ashes are suspended in water
and feathers in air when these are agitated, and sink to
the bottom when they are at rest. For this reason there-
fore the movement should be slower towards the end,
the agitation being greater.

I4 Rey.
ESSAY VI.
Heaviness is so closely united to the primary matter
of the elements, that when these are changed
one into the other they always retain the same
weight.
My chief care hitherto has been to impress on the
minds of all the persuasion that air is heavy, inasmuch
as from it I propose to derive the increase in weight of
tin and lead when they are calcined. But before showing
how that comes to pass, I must make this observation—
that the weight of a thing may be examined in two ways,
viz. by the aid of reason, or with the balance. It is
reason which has led me to discover weight in all the
elements, and it is reason which now leads me to give
a flat denial to that erroneous maxim which has been
current since the birth of Philosophy—that the elements
mutually undergoing change, one into the other, lose or
gain weight, according as in changing they become
rarefied or condensed. With the arms of reason I boldly
enter the lists to combat this error, and to sustain that
weight is so closely united to the primary matter of the
elements that they can never be deprived of it. The
weight with which each portion of matter was endued at
the cradle, will be carried by it to the grave. In what-
ever place, in whatever form, to whatever volume it may
be reduced, the same weight always persists. But not
presuming that my statements are on a parity with those
of Pythagoras, so that it suffices to have advanced them,
I support them with a demonstration which, as I con-
ceive, all men of sense will accept. Let there be taken
a portion of earth which shall have in it the smallest
possible weight, beyond which no weight can subsist :
let this earth be converted into water by the means
known and practised by nature: it is evident that this
Essays. I5
water will have weight, since all water must have it,
and this weight will either be greater than that of the
earth, or less than it, or else equal to it. My opponents
will not say that it is greater, for they profess the con-
trary, and I also am of their opinion : Smaller it cannot
be, since we took the smallest weight that can exist:
there remains then only the case that the two are
equal, which I undertook to prove. What is shown of
this particle may be shown of two, three, or a very great
number—in short, of all the element, which is composed
of nothing else. The same proof may be extended to
the conversion of water into air, of air into fire ; and,
conversely, of the last of these into the first.
ESSAY VII.
A means of knowing what volume of air is produced
from a certain quantity of zwater.
Philosophers have often spoken of the extension which
a solid element acquires on changing into one more rare,
and have endeavoured to assign its proportion : but I
have no recollection to have read anything supported by
a valid reason or experiment. Now, since in the pre-
ceding essay I have spoken of that ampliation, the know-
ledge of which opens the door to many beautiful and
admirable artifices, I will not deprive the curious reader
of a means which I have excogitated to bring this to the
proof and know with certainty to what volume a certain
quantity of water will expand on being transmuted into
air; which means can be made of service and fitly
applied to the other elements. Let there be constructed
a wide tube of brass of suitable dimensions, well polished
within, quite open at one end and closed at the other
save for a very small aperture in the middle : let there be
placed in it a plug such as that of a syringe, which can
16 - Rey.
slide everywhere with ease, and is so truly fitted that no
air escapes. This being pushed to the bottom, let there
be applied to the small aperture and tightly fastened
into it a tube issuing from an AEolipyle or philosophic
bellows. Let this, filled with water, be placed on a fire.
The water being rarefied and transmuted into air will
then issue from the small orifice, and entering the wide
tube will gradually push along the plug, seeking its
liberty, until all the water has been converted into air.
The volume of the tube
and of the AEolipyle that
is filled by it will show
the expansion which this
matter has experienced.
If anyone wishes to know
the same more easily,
though not so exactly, let
him take all the bowels
of a pig or other animal
after having cleansed
them; and, having made
them flat and empty of
air, let him put them into
a vessel full of water
closed tightly by a lid
with a little hole at the
top to allow the water to
escape: one end of the
said bowels projecting through the vessel by another
hole and being attached to the tube issuing from the
AEolipyle, which, filled with water and set upon the
fire, will blow into the gut the air into which the
water will be converted. As the intestine swells, the
water in the vessel will escape through the small hole in
the lid, and, when collected, will show the Space occupied
|


Essays. 17
by the air in the intestine, to which if we add the volume
of the AEolipyle we shall obtain what we desired. To
these well-assured means I add the following, which
seems not unpromising, to convert air into water, and
ascertain the diminution of volume. Let the hole in the
wide tube above-mentioned be closed, and push in the
plug with great force as far as the compression of the
enclosed air will permit; and, it being arrested there,
lest it should recoil, let the whole instrument be exposed
to a freezing atmosphere during an entire night. The
air compressed within it will freeze or turn into water,
only leaving the volume of the air which can remain
free. By measuring the water or the ice, we shall be
able to judge of the diminution. I have not made these
experiments: if some enquirer forestall me, I beg of him
to advise me of it as only recompense of having shown him
the method, in order that I may be spared that trouble.
A. shows the AEolipyle. B. the tube issuing from it
and entering the wide tube C. D. the plug which moves
within it. E. the handle for pushing in and withdrawing
the plug.
ESSAY VIII.
No element exhibits weight in itself, and why.
I retrace my steps, and affirm that the examination of
weights which is made by the balance differs greatly from
that which is made by the reason. The latter is only
employed by the judicious : the former can be practised
by the veriest clown. The latter is always exact: the
former is seldom without deception. The latter is
attached to no circumstance of place; the former is
commonly exercised only in the air, and occasionally,
with difficulty, in water. It is from this that the error I
have combated (that air is without weight) draws an
argument which may dazzle feeble eyes, though not clear.
B
I8 Rey,
seeing ones. For, balancing air in air itself, and finding
no weight in it, they believed that it had none. But let
them balance water (which they believe to be heavy) in
water itself, and they will find no weight in it either: the
fact being that no element shows weight when weighed
in itself. Everything that exhibits weight in air, every-
thing that exhibits weight in water, must in an equal
volume contain more weight (on account of the excess
of matter) than the air, or the water, in which the equili-
brium is made. From this I now deduce the cause,
which few have perceived. Whatever shows weight in
air (and of water the same may be said) cleaves it, thrusts
it aside and forces it to give way, so that it may sink to
the ground. This is called exercising its forces and its
action in the air. Now it is the case that no agent acts
in a medium like itself, all action presupposing some
contrariety. Heat will never act on another equal heat,
but the two heats will embrace and unite their actions,
and by this union become a single agent instead of two
as at first. If a great heat act on a lesser heat, it is
because there is here a dissimilarity, and in some measure
a contrariety, the lesser heat taking the title of cold when
compared with the greater heat. Thus air cannot act
by heaviness in air equally heavy : these two airs unite
rather and make one weight. But whatever is heavier
than air, by the dissimilarity and nascent contrariety of
this excess or defect, will act in it, cleaving it, putting it
aside, and making way for itself through it to sink down-
wards. And if air does not show its weight in air itself,
on account of the equality of their heavinesses, with
greater reason will it not show it in water, which is
heavier. For even if it be placed under the water, it will
not sink lower; the weight of the water which is upon it
only constraining it to seek a higher place, not permitting
it to abide beneath. -
Essays. I9
ESSAY IX.
Air is rendered heavy by admixture of maſter
heavier than itself.
It is my design to show that it is the air that mixes
with the calx of tin and of lead on calcination which
augments its weight, and this would be impossible if I
did not remove a somewhat grave difficulty which here
presents itself. For one might ask, how can what I say
take place, since the examination of the weight is made
by means of the balance and in air, in which air can
have no weight according to the doctrine deduced in the
preceding Essay? To remove this doubt I say that air in
its parts can be altered and increased in weight, so that
the parts thus changed and made heavier, when balanced
in pure air, will make their heaviness visible. But what
is this change which causes the increase in heaviness?
I remark that it may happen in three distinct ways,
namely by the admixture of some heavier foreign matter,
by the compression of its parts, and by the separation
of its less heavy portions. In the first place let us con-
sider the first mode, and then the two others. It is
certain that air is susceptible of several matters heavier
than itself: such are the vapours and exhalations pro-
ceeding from the water or from the earth. A portion
saturated with these matters will weigh more than an
equal portion of another air which has nothing of the
kind in it. Thus sea water weighs more than the fresh
water from rivers, the former containing much salt, from
which the latter is free. Note, I pray you, how, in foggy
weather, when your high windows are first opened, the
air laden with mists enters into your chamber. Do you
not conclude that the former weighs more than the latter,
since it cleaves it and sinks in it? Fill a globe with
this nebulous air : it will weigh more than the same filled
2O Rey.
with an air pure and without admixture. This experi-
ment is in harmony with reason which states, If to two
equal weights we add two unequal weights, the two
weights will no longer be equal, and that will be the
greater to which the greater weight has been added. If
therefore we take for example two portions of the same
air, each containing ten cubic inches of volume, and to
one be added two inches of water, and to the other two
inches of air, who does not see that these two portions
will be equal in volume but not equal in weight, and that
the one which has the water in it will be heavier P This
is so manifest that I abstain from saying more concerning
it, seeing, besides, that the increase in heaviness brought
about in this way is of little moment to our subject. So
let us pass to the others.
ESSAY X.
That air is rendered heavy by the compression
of its parts.
The second fashion by which air increases in weight is
the compression of its parts: for nature has willed, for
reasons known to herself, that the elements may extend
or contract up to certain limits which she has prescribed
to them. In this space we see a portion of an element,
now closely compressed, now extended spaciously. See
this pot half-full of water, under which the cook is about
to make a good fire: the water will dilate until it spills
over the edge; but, the fire being extinguished, it will
shrink, and return to its first condition. Take this
syringe in which the plug is sunk half way, and the hole
in front well stopped up : push forcibly and you will
reduce the enclosed air to a small bulk. Draw the plug
towards you, you will not draw it out altogether, but you
will extend the air to more ample dimensions than it
Essays. 2I
formerly possessed. The air being thus compressed, do
you doubt that it weighs more than a free air, since in
an equal space it contains more matter? If the reason
given above in the eighth Essay does not satisfy you,
come to the proof of it. Fill a globe with air forcibly by
means of a bellows: you will find a greater weight for
this full globe, than when it is empty. And by how
much P By as much as the air contained in the balloon
weighs (by the reason) more than the air in an equal
space when it is free. Several persons have remarked
this excess of weight of the full globe over the empty
globe, but it has not come to my notice that any one has
hitherto known the cause of it. I leave aside people of
low esteem : the learned Scaliger, the true genius of
Aristotle, did not know it: for in Exercitation czzi.
against Cardan, he follows the high road, holding that
pure air is light, and that heaviness accrues to the globe
because the air near the surface of the earth, such as is
blown into the globe, is commingled with vapours and
those small terrestrial bodies which are seen manifestly
in the rays of the sun. But alas ! what does this com-
mingling avail him, since the examination is made in an
air quite similar P Assuredly it could show no heaviness
if compression did not come to its aid. And if the
globe were forcibly filled with the purest air that exists
in nature, nay, with elementary fire, reason insists that
it would show weight, being balanced in the same air
in the first case, and, in the second, in the same fire.
This compression of air is a rich field in which men of
intelligence will cull rare artifices. It is from it that
the sieur Marin Bourgeois, of Lisieux, has derived his
arquebus: which I invented myself several years ago,
and before the sieur Flurance had described it : but
which excels above that of Marin (I say it without
vanity) by reason of yielding much more force. I could
22 Rey.
communicate to the reader another gentle and profitable
invention which I have drawn from this: but designedly
I keep silence concerning it, in the hope that one day I
may have the pleasure of presenting a very humble
petition to his Majesty, and that he will honour me with
a license to make use of it for a time to the exclusion
of all others, in order that I may be in some measure
repaid the charges which will be necessary to bring the
said invention into use, as well as several others which
I have hitherto held concealed.
ESSAY XI.
Air is rendered heavy by the separation of its
less heavy parts.
Before speaking of the third method by which air is
rendered heavy, namely by the separation of its less
heavy parts, I begin by stating the following truth, which
cannot be gainsaid; That if from anything whatsoever
the less heavy parts be abstracted, the residue will be
rendered heavier : I do not say heavier than the original
thing in its entirety, but only heavier than a portion of
it equal in volume to this residue. Separate the silver
which that shameless goldsmith mixed with the gold in
the crown of King Hiero: the gold remaining will
weigh more than an equal portion of the whole crown.
What you do here by art, nature does by her own
industry, having for sole tool heat, which serves her
worthily in this work. See these salt-workers lead the
sea-water by channels into their shallow pits; they know
that the heat of the sun by subtilizing the water will
sublime it into air, leaving the salt, the heaviest part,
below for them. The alchemist, nature's very ape,
wishing to imitate her, puts on the chafing-dish the
infusion of his rhubarb, in order that the liquor may be
Essays. 23
exhaled and the extract remain behind for him. But
when he has need of that part which when subtilized
escapes, he cunningly traps it on the way by means of
the hood which he applies to his alembic. By this
device he possesses himself of aqua vita, which is less
heavy than the wine from which it is derived: and the
wine less heavy than the dregs which remain after the
distillation. Heat acts in this way on all manner of
liquors, rarefying some parts, making others more dense,
and always separating them on account of their weighing
more or less. It produces the same effects for us in the
air, and in order that you may note them, turn, I pray
you, towards those fields on which the sun has darted
his rays during the whole day. You imagine, I wager,
that the air which touches it directly is more subtle and
less heavy than it was this morning P. How different is
the fact It is much more dense, and in consequence
much heavier. For how has heat subtilized the air
without having raised it? and how raised it without
the descent of a heavier air P. Nothing mounts upwards
of itself; it is the fall of something else that pushes
it. It has without doubt separated and raised the
more subtle parts, leaving below the dregs so to speak,
just as in the distillation of liquors. And if this reason
persuade you not that the heated air is rendered dense
and heavy, believe at least the evidence of your senses.
I undertake to make you feel it so with your hands,
and see it so with your eyes. Now that it is midday,
do you not find this air hotter than it was a quarter
of an hour after the sun had risen P. It is not however
that the Sun has bestowed upon it a greater degree
of heat, because this he possesses invariable, and dis-
tributes in the sphere of his activity with an ever
equable tenour: in such wise that piercing as it were the
air with his rays without resistance, he communicates to
24 Rey.
it all his light, and likewise all his heat, which has not
itself increased although its action is increased on account
of the condensation of its object: for the more subtle
parts of the air being elevated little by little, the others
are found more frequently here below and are gathered
more together in one place. And from this greater con-
centration comes the greater action. This can be explained
by considering the elementary fire, which although it is
hot to an extreme degree does not yet burn on account of
the extreme rarefaction: but heated iron burns violently;
not because it is hotter (for how could it be hotter than
the extreme heat?) but because it is denser, containing
more particles in an equal space. So much then for
touch : let us proceed to the other sense. When this
morning the sun commenced to irradiate the horizon, the
air by its subtlety was entirely hidden from your eyes:
but now, can you not see how it quivers above these
furrows P. It is because it has become denser, and
acquired more corpulence, that it is rendered at all
visible. So, I think I have acquitted myself sufficiently
of what I promised, and now it is time to proceed
further and say that if the simple heat of the Sun thus
renders our lower air dense and heavy, driving aloft its
more subtle, and keeping below its stouter and more solid
parts, what will not the vehement heat do, which the
throat of a furnace heated by a glowing brasier disgorges
for a great space of time? A quantity of aqua vitae
placed upon it within a vessel will promptly vanish.
Common water and all manner of liquors will be exhaled
in a few hours. Air nevertheless will subsist in it (there
being no other body to fill its place), but it will be an
air dense and heavy as possible; an air. I would almost
say which is no longer air, but an altered and unnatural air,
its subtle fluidity being changed to a viscid grossness.
For the violence of the fire subtilizing as much air as
Essays. 25
reaches it, will drive off to a distance an immense
quantity, only leaving around itself, of all this immense
quantity, a species of lees which, owing to its viscous
heaviness, cannot take its flight.
ESSAY XII.
7%at fire by its heat can make homogeneous bodies
dense.
I know not what fatal calamity has invaded the
sciences, for when an error is born with them and with
the lapse of time becomes as it were fixed there, those
who profess these sciences will not suffer its withdrawal.
Exception has already been taken to the doctrine of the
preceding Essay, and the objection has been raised that
though fire can render heterogeneous bodies denser by
separating their more subtle particles, these being of
diverse nature, it cannot do the like with homogeneous
bodies, inasmuch as it acts uniformly on all their par-
ticles, and has no other action than to expand and dilate
them all equally, so that in that way air could not be
made denser and rendered heavy by the force of heat. I
recognise this doctrine (which is opposed to my belief), to
be taken from the school of Philosophers whom I honour
as great surveyors of nature, but I frankly confess that I
have sworn to the words of no one of them. If the
truth is with them, I receive it: if not, I seek it else-
where. Let us see if they have found it in this matter.
Homogeneous bodies, they say, are such as have all their
parts of the same nature: or else are such as have all
their parts of the same name and the same definition as
the whole. I even admit that when fire acts on such
bodies it dilates them of itself and by its own virtue:
but reason teaches me, and experience confirms it, that
26 Rey.
by accident, at it were, and after the subtilization and
separation of some particles, the others which remain are
denser and heavier. If that is denied me, and if the
above-mentioned doctrine is rigorously upheld, as if fire
could neither of its own nature nor by accident make
homogeneous bodies denser, then I undertake to prove
that it is false, and could produce a cloud of examples
to the contrary; but the courteous reader, for whom I
labour, will be content with a few. Vitriol is a homo-
geneous body, since its particles have the same name and
the same definition as the whole; now fire acts upon it
in a retort in such wise that we perceive separately its
phlegm, its oil, and its coloothar; parts differing in density
and in weight. Turpentine is a homogeneous body, the
smallest particle of it being turpentine no less than the
whole; but when it is placed in an alembic, the fire by
its action dilates some of its parts, and condenses others,
separating its water, its spirit, its oil, and its colophonium,
the difference of which in respect of weight and subtlety
is notorious. I have already spoken of wine (also a
homogeneous body), how when it is subjected to the
forces of fire on distillation, it is expanded and dilated in
such fashion as to yield aqua vita and the petite eau as it
is called : but the residue is the thicker, the more of that
water or even of phlegm there has been removed from it.
But why do I trouble myself to produce these examples,
since it is evident that from such substances there may, by
means of fire, be obtained salt, sulphur, and mercury, parts
which differ sensibly in tenuity and weight. It is therefore
untrue that fire dilates all their parts equally. I can well
foresee that my opponents will attempt evasion by saying
that the examples which I submit are compound sub-
stances, and that it.could not be so with simple substances.
Thus however I have been able to convict this maxim of
falsity when taken, as it is advanced, in its generality and
Essays. 27
extended to all homogeneous substances. Let us see if
truth follows better in its track, when it is adapted to
simple substances.
ESSAY XIII.
That fire can make water denser.
Water is a simple substance beyond question. And
yet fire, acting upon it, dilates some of its parts and con-
denses the others: although, as I said above, the first
action is that proper and natural to it, and the second
accidental. Pour a pipe of water into an alembic, heat
it with fire according to the rules of the art, and draw
from it by distillation, to begin with, one pot. It is cer-
tain that the water in this pot will be more subtle than
that which you put into the alembic. If any one, driven
by the desire of contradiction, gainsay it, let him go to
the Chemists for a refutation, who, not being able con-
veniently to make their extracts with common water, are
accustomed to employ distilled water, or even dew, which
is but water passed through the great alembic of nature :
for such water, being more subtle, penetrates more readily
the substance of the simples, and extracts from them more
easily their virtue and tinctures. Its greater diuretic
power and its smaller weight (inseparable companion of
a smaller density) will abundantly testify to all the truth
of my statement. Now if the water in this pot is more
subtle than the water put into the alembic, that which
remains must be more dense, inasmuch as condensation
of necessity follows the separation of the more subtle
parts. This will be the more evident if you continue the
distillation, for drawing off pot after pot until nothing
further remains, the last will be sensibly denser and
heavier than the first ; the sensible difference coming by
small degrees, which (although imperceptible) will exist
28 Rey.
between the first and second, second and third, and so
on in order to the last. And this difference will not only
exist from one pot to another, but from glass to glass,
and even from drop to drop : it being reasonable, since
the two extreme drops differ manifestly in density and
weight, that this difference goes on increasing from the
beginning to the end, with the increase of the number of
drops which come from the distillation. From this it is
apparent, that as in heterogeneous bodies, fire separates
the particles which are of diverse nature; so in homo-
geneous bodies it disjoins the particles which differ in
tenuity, and then gravity assumes the office of arranging
them in order, and assigning to each his place, even in
fluid matters, whose more ponderous particles ever reach
the bottom, making a path for themselves through those
which are less ponderous, and sinking necessarily among
them. So that if all the water which would distil from
the above-mentioned pipe should fall in order into a tube
of sufficient length and as thick as a quill, it is credible
that the second drop would sink into the first, the third
into these two, and so on consecutively to the last, which
being the heaviest would traverse all its predecessors and
occupy the lowest place, so that the drop which fell first
would find itself at the end in the highest place. And
although this continuous passage would bring some sort
of mixing of these particles in its train, still it would not
be such as to prevent the difference in weight of the
higher and lower portions being notable. Now if anyone
because he cannot actually see the sinking of the drops
is inclined to doubt it, let him place and dextrously join
the mouth of a phial full of water to the mouth of a
like phial filled with claret wine, and he will perceive a
similar phenomenon: for the water being heavier will
sink into the lower phial through the wine, forcing it
plainly to rise into the upper phial. Does not wine even
Essays. 29
arrange its more subtle part at the top of the cask and its
grosser part at the bottom, in virtue of the weight of one
being greater than the other? Common people believe
also, and not without reason, that the first glass poured
from a can is more subtle and vaporous than those
following. This difference which is observed in so small
a vessel could easily lead one to the opinion that if a
tube only an inch wide and extending several fathoms
down, were constructed, and were filled with wine and
allowed to stand for some time, the higher portion, if not
altogether aqua vita, would approach it closely in tenuity
and efficacy. A fine invention, truly, to extract spirit
from wine without the aid of fire, if the thing went
actually thus, and the difficulty of making the instrument
did not prevent its use ! All these remarks serve to lead
up to a general assertion, to wit, that in all fluid sub-
stances, composite as well as simple or elementary, the
higher parts always differ from the lower in subtlety and
heaviness: and that this difference is distinguishable
into as many degrees as their matter can be divided by
their height into distinct parts. So much so that if we
conceive a line drawn from the lowest of one of the fluid
elements (such as the air) to the highest surface, then
there will be as many distinct degrees of weight and
subtlety in this element, as the line can be divided into
distinct parts (I mean materially, to avoid sophism) and
the uppermost part will always be more meagre and less.
heavy than the second, the second than the third, and so
on to the end. For to attribute the same corpulence to
all the parts of each element is to deny the evidence of
the senses, which make us judge air (for example) to be
more subtle at the top of a mountain than at the bottom,
on the plain. And also when the heat of the Sun or of
our fire subtilizes it beneath, it mounts upwards, without
question, until it meets its like according to the degree of
3O Rey.
subtlety it has acquired. Besides if this equality did
exist everywhere in the element, there would be no reason
why one piece should be below rather than above, when
it is at rest. For to commit that to chance and adven-
ture would be offensive to the incomparable wisdom of
the Author of Nature, who has made nothing therein
without weight, number, and measure, and established
in it such order that nothing happens fortuitously and
without cause. I conclude then that this arrangement
comes from weight and not elsewhere. And to end this
Essay, I say that everyone can now see that fire acting
on the simple substance water, does not extend all its
parts equally, but in dilating some, separates them,
whence it follows that the others are rendered denser.
Thus the maxim which is in contestation will not be
true. Nay but, some will say, this must be shown of the
air, on which moves the pivot of the controversy. That
is their last refuge, and I am about to deprive them of it.
- ESSAY XIV.
That Fire can make Air denser.
The reasons deduced from the eleventh Essay might
suffice to convince an unprejudiced mind that when fire
heats air it subtilizes and separates some of its particles,
and that this separation is of necessity followed by the
others becoming denser and heavier. But since this
truth encounters obstinate opposition, I demand, to show
it more clearly, that a laboratory be assigned me in the
region of the elementary fire adjoining the region of the
air : and in it I will give them ocular demonstration of
what they refuse to believe. For, as the vessels which
we here call empty are nevertheless full of air, so they
would there be full of fire. And as when we here pour
water into an alembic, the air previously enclosed quits
Essays. 3 I
the place, so there the fire will give place to air poured
in, which being set on the furnace, will distil drop by
drop into the receiver: and the first measure to be
collected will be more subtle than the second, this more
subtle than the third, and so to the end. What is more,
the difference in subtlety and heaviness between the first
and last measure will be as perceptible as the difference
in the case of distilled water. Now if any one laugh at
my request, let him know that the great Archimedes on
a like occasion asked to be given a spot in the region of
the air to apply his engines, and he would lift the whole
earth. Not that he thought that what he asked could be
granted (for he was neither a fool nor a madman in the
opinion of the wisest), but he did it, resting on the certi-
tude of his demonstrations and to give a clearer evidence
of the truth of his assertion. My request has the same
end. Whoever will see a thing approaching this, without
resorting to the impossible, let him place on the furnace
an alembic of size greater than common, and having
attached to a tube at the highest point of the hood a
bladder empty of air, let him begin to make the fire.
Then the air in the alembic will dilate, and, the original
space being unable to contain it, will issue forth and fill
the bladder. There will now be put on another bladder
precisely equal to it until it also is filled, and this chang-
ing will be continued till the end. I say that the last
will be heavier than the first. Whoever doubts this, let
him essay it, and follow the procedure exactly. By the
degrees of this meditation my mind has been raised to
greater things, of which nevertheless I will not speak as
not touching this matter, and as being difficult, not only
to practise, but to comprehend. I come to another
demonstration by which the truth that I defend will be
more than visible. Let a cannon be set directly on its
breech with the muzzle upwards, and let there be thrown
32 Rey.
into it a ball of its calibre made red-hot in the fire. It
is certain that the air contained in the bore of the gun is
so meagre in substance, and in quantity so small, that
the ball in passing will impress on it all the degrees of its
heat. Notwithstanding this, if you put your hand in the
muzzle you can keep it there easily at first ; but a little
time afterwards you will not be able to do so. Not that
the air has increased in degree of heat : it has rather
decreased, and so likewise has the shot, which cools little
by little: but as it is rendered denser by the separation
of the more subtle parts of an abundance of air which
will rapidly flow thither, it will act more powerfully, as I
have elsewhere said. In the second place, the air which
will be seen quivering over the muzzle (which will only
be at the beginning) constrains us to admit that it has
there become denser; for we cannot say that it is due to
the vapours or exhalations rising from the gun: every-
thing in it is too dry and solid to let any part of itself
escape. Thirdly, if the air over the muzzle did not
become denser it would not blur the objects on the other
side which we see through it. And a swaying motion of
the air cannot be given as an excuse, since I see dis-
tinctly the charms of that lady across the air which she
agitates with her fan. And I also see clearly all sorts of
objects through the air shaken by the north wind when it
blows and whistles noisily. Finally, if a flock of wool
well teased out is placed in the muzzle of the cannon, it
will not descend ; and if it is pushed some distance
down, it will mount again suddenly ; which would
assuredly not happen if the air were not denser than at a
distance from the cannon where the flock falls down-
wards very readily. These reasons, although not gross,
are nevertheless so palpable, that they will convince all
that the heat has made the air denser beyond the muzzle
of the cannon. Now having made the air dense so high
Essays. 33
up, what will it have done, I ask you, at the bottom of
the cannon near the ball? Taking the ball out after it
has cooled you will find it more whitish than it was
before being made red-hot in the fire; as if the dense
-and adherent air gave it this colour, which becomes dim.
and vanishes with lapse of time, even in a damp place;
inasmuch as the ambient air dissolves that which adheres
to the ball and recalls it to its original state. As a last
dish, I wish to serve up to the reader a remark which
may be to his taste. Those who pursue Medicine
worthily will sometimes find themselves called upon to
visit asthmatics, who, gasping in bed in hot little rooms,
can only draw their breath with great difficulty. Per-
ceiving which, they cause the windows to be opened,
conduct them thither, and make them inhale the external
air, which gives them great relief. If you ask these
gentlemen whence such a prompt alleviation comes to
the sick persons, they will tell you that it is because the
air of the room, being too hot, cannot furnish the heart
with the necessary refreshment, which the external air
accomplishes better by reason of its coldness. Now,
gentlemen and honoured colleagues, having undeceived
myself on this point by the preceding meditations, permit
me, I pray you, now to undeceive you. It is not the heat
of the air in the room which causes this gasping, on
account of it not being able to refresh the heart, but
rather its density which retards its course through the
obstruction of the lungs, so that it cannot furnish the
heart in time with matter sufficient for the generation of
the vital spirits, which fresh air, being more subtle, can
do. And that you may not think I advance this without
reason, note this person sick with fever who lies in the
same room, in which the enclosed air refreshes him
sufficiently, although he has greater need of it. And if
the fever attacks the asthmatic (which you will hope for
C
34 Rey.
his good) and dissipates the matter which stopped up the
conduits of the lungs, does not the same air then refresh
the sick person sufficiently, although his need of it has
augmented P Does not the same occur when the dissipa-
tion is performed by the use of Diasulphur, which Galen
composes, as you well know, of Sulphur, of pepper, and
of mustard-seed in equal proportions P It must be then
that heat has rendered the air more dense by driving off
the most subtle portions—which is said to be so im-
possible. I comprehend already that to elude the force
of so many reasons and experiments, I shall be told that
the examples I have brought forward can indeed be veri-
fied in our gross and impure air, but that it would be
otherwise with pure air, if there were such in nature.
And assuredly I wish for nothing better to dispose me to
a song of triumph. For does anyone believe that I think
the sieur Brun and the others who have performed the
augmentation in question, procured some purer air, by
letters of exchange, from beyond the bounds of nature ?
*
ESSAY XV.
Air decreases in weight in three fashions : the
'balance is deceitful: means of remedying it.
I resume the thread of my discourse which I had
somewhat interrupted to remove the objection which
had been raised, and so better clear up this matter: and
assert that in the three preceding Essays, namely in the
ninth, tenth, and eleventh, I have declared the three
different means by which air increasing in heaviness may
show this when balanced in a pure and free air. Now
the law of contraries insists that by three opposite means
it may diminish in heaviness. These means are the
separation of some heavier foreign matter: the exten-
sion of the air to more ample limits: and the extraction
Essays. 35
of its heavier particles. But because the comprehension
of the former throws sufficient light on the latter, I am
spared a more ample explanation, begging only that the
reader remark that this augmentation or diminution of
weight of which I have spoken in the said Essays, always
refers to a portion of air compared with another of equal
bulk. For when we have no regard to the bulk or
volume of the thing, if we examine its weight by the
reason, I say that there is nothing which increases in
heaviness but by the addition of matter, nor which
decreases in heaviness but by the subtraction of matter:
so inseparably are matter and heaviness joined, as has
been shown above in the sixth Essay. But if we make
the examination by the balance, we meet with a case in
which without addition or subtraction of matter the thing
will appear heavier or lighter: namely by shrinking, or
dilatation. And it is this examination alone of which
the ancients had cognisance, when they supposed that
the elements in their mutual conversion increased or
decreased in weight, when only the extension increased
or diminished, by the sole aid of Nature so expert in
doing this: not that the weight of things may not be
increased or diminished artificially by dilating or com-
pressing them. Beat a piece of iron for a long time in
the cold and you will unite its parts and lessen its
volume: then it will show a greater weight when placed
on the balance. On which, also, if you put a ball of
feathers tightly tied together, it will weigh more than the
same left loose. From this I infer what was previously
touched upon in passing, that the balance is so fallacious
hat it never indicates to us the just weight of things,
except when in it there are confronted two weights of
the same matter and figure, like two leaden balls. But
two ingots for example, one of gold and the other of
iron, which the balance shows to be equal, are not so,
36. Rey.
nevertheless: for the iron weighs more by as much as
the air weighs (according to reason) which would be
contained in the excess of space occupied by the iron
over the gold. Which difference I could show precisely
in everything that is weighed, and reduce all to the just
weight, if I had made the experiment which I explained
above in the seventh Essay. #,
. ESSAY XVI.
Formal response to the question, why Tin and Lead
increase in weight when they are calcined.
Now I have made the preparations, nay, laid the
foundations for my answer to the question of the sieur
Brun, which is, that having placed two pounds six
ounces of fine English tin in an iron vessel and heated
it strongly on an open furnace for the space of six hours
with continual agitation and without adding anything to
it, he recovered two pounds thirteen ounces of a white
calx; which filled him at first with amazement, and with
a desire to know whence the seven ounces of surplus
had come. And to increase the difficulty, I say that it is
necessary to enquire not only whence these seven ounces
have come, but besides them what has replaced the loss
of weight which occurred necessarily from the increase
of volume of the tin on its conversion into calx, and
from the loss of the vapours and exhalations which were
given off. To this question, then, I respond and sustain
proudly, resting on the foundations already laid, “That
this increase in weight comes from the air, which in the
vessel has been rendered denser, heavier, and in some
measure adhesive, by the vehement and long-continued
heat of the furnace: which air mixes: with the calx (fre-
quent agitation aiding) and becomes attached to its most
minute particles : not otherwise than water makes heavier
Essays. 37
Sand which you throw into it and agitate, by moistening
it and adhering to the smallest of its grains.” I fancy
there are many who would have been alarmed by the
sole mention of this response if I had given it at the
beginning, who will now willingly receive it, being as it
were tamed and rendered tractable by the evident truth
of the preceding Essays. For those without doubt whose
minds were preoccupied with the opinion that air was
light, would have rushed to oppose it. Why (they would
have said) does not one extract cold from heat, white
from black, light from darkness, since so much heaviness
is extracted from air, a thing inherently light? And those
who chanced to have bestowed their credence on the
heaviness of air, would not have been able to persuade
themselves that it can ever increase weight, being
balanced in itself. On this account I was constrained
to show that air had weight; which was recognisable by
other means than the balance: and that even with the
latter, a portion previously changed and made denser
could manifest its weight. All this I have done as
briefly as I found possible, and without advancing any-
thing not strictly germane to this matter: to elucidate
which at all points it only remains for me to state and
refute succinctly some opinions which others have held
or might hold; and to resolve the objections which
might be made to my answer.
ESSAY XVII.
That it is not the disappearance of the celestial heat
giving life to the lead, or the death of the latter,
which augments its zweight on calcination.
of all those whom I know to have written on this
question, Cardan presents himself first, and asserts in
the fifth book de Subtilitate that lead on conversion into
38 Rey.
cerussa, or on calcination, augments its weight by one-
thirteenth, afterwards giving this reason—That the lead
dies, inasmuch as the celestial heat, which was its soul,
vanishes, its presence having previously given it life and
lightness, as its absence gives it death and heaviness.
This he confirms by the example of the animals, which
death renders heavier by the extinction of this celestial
heat, which, according to his belief, is the soul of animals
as well as of all other mixed and composite bodies. This
opinion has several shortcomings (to say nothing worse).
Firstly, because it attributes life to the lead. Secondly,
because it maintains that the presence of celestial heat
makes the lead light, and its absence heavy. Thirdly,
because it gives the same reason for the increase of
weight of lead on calcination, and of animals on their
death. Nothing of all that is the case. For touching
life, how can lead have it, since it is a homogeneous
body, without distinction of parts, without organs, and
without any vital effect or action ? If it moves down-
wards, so does cerussa, which is only its dead body: if
it is cooling, cerussa is cooling also. Then how could it
preserve that life in the million forms it can assume and
put off, remaining always lead? How in a furnace (and
this is a much greater marvel) in which it can be kept
molten a day, a month, or even a whole year? It would
need a very tenacious soul, to suffer so much without
dislodging. Everybody, too, agrees that from death to
life there is no return. Yet chemists promise us that if
we moisten the calx of lead and mix it with water in
which barilla has been dissolved, and having dried it,
place it in a crucible which has only a small air-hole
open, and expose it to a hot and quick fire, we shall
reduce it to its first condition. As regards his notion
that the celestial heat makes substances light Scaliger
raises the pertinent objection that the celestial sphere
Essays. 39
which abounds in this heat, being the source of it, must
itself be light, and in consequence univocal with the
other bodies; which is ridiculous. The loss of this heat,
also, cannot render them heavy, for I have proved in
what precedes that nothing augments in weight but by
addition of matter or by shrinking in volume, of which
there is nothing here: for the heat in vanishing can add
nothing to the lead, and the volume appears to be visibly
augmented, the solid and compact lead being broken
down into so many particles that their number borders
on the infinite. It would also follow that plants become
heavier when they die, their celestial heat being dissi-
pated : but the opposite is evident to all. As to the
heaviness which increases in animals on their death, its
cause is far removed from that which augments the weight
of lead on calcination. As long as the animal lives, its
natural heat subtilizes, expands and augments the dimen-
sions of the humours, flesh, and every part of it which is
dilatable: and being lost on death, all the above, on
cooling, shrinks and contracts, whence comes the increase
in weight, as I have often said. What is there in lead
like this P. Thus the opinion of Cardan seems so frivol-
ous, that I am grieved that a great man, who is rightly
held in high esteem throughout the universe, should have
declared to me a few days ago that he inclined towards it.
ESSAY XVIII.
That it is not the consumption of the aërated particles
which augments the weight of the lead.
Scaliger has bound himself up so closely with Cardan,
that I cannot separate the two ; so here as elsewhere
he must follow him. In Exercitation ci, section 18, he
states that the augmentation in weight of calcined lead
comes from its aerated particles being consumed by the
4O :-- Rey.
fire: for the same reason, says he, as baked tile weighs
more than unbaked. Oh how the superficial resemblance
of things sometimes deceives fine understandings This
great man seeing that the calx of lead and the tile after
treatment with fire both become heavier, thinking of the
same effect, has sought only one and the same cause.
The causes are very diverse notwithstanding. The tile
increases in weight by decreasing in extension : the calx,
because of the addition of matter. And in order to
make this better understood, who does not know that
tile is made of a rich and sandy earth kneaded up with
water? And that the Sun absorbing its humidity leaves
in it an infinite number of little cavities which were
originally filled with water? When it is baked in the
kiln, the heat softens it, like metals, and takes it to such
a point that it almost melts, and does in fact melt if the
heat is excessive. During this softening the particles
shrink together, unite, and become attached to each
other; the cavities disappear, and contraction thus occurs:
thence comes its great weight, as I have often stated. As
to lead, it melts on the fire, as is well known; and being
melted, fills the vessel at all points, leaving no trace of
air within itself, in accordance with the privilege that
nature has granted to ponderous and fluid bodies of forcing
upwards bodies which are less so, and sinking down within
them. This lead taken off, loses its heat little by little :
while it closes up and coagulates, shrinking into itself,
and diminishing in volume, as is apparent from the
dimple which is seen on the surface when it has cooled:
so that it is impossible to imagine the presence of air
enclosed in that heavy mass. Melt it again and calcine
it, you will find it heavier: not from the consumption of
aérated particles, seeing that there were none in it; but
by reason of the condensed air which has united with it,
as I have already said. And as a matter of fact if it lost
Essays. 4 I
some aërated particles, would it not decrease in volume 2
On the contrary it increases. And again, why do not
stones and plants increase in weight on calcination if
that reason be valid P I infer from the above that the
consumption of aerated particles never augments the
weight of things when shrinkage does not result; which
not being the case in our affair, cannot be admitted as
the cause of the surplus weight of which I discourse. I
add in conclusion that the air which is forced by a syringe
into a globe already full of it, diminishes the weight on
escaping, far from increasing it as Scaliger fancies. It is
true that this is met with only in this one case.
ESSAY XIX.
That it is not soot which augments the weight of
the cala.
I read in the tenth chapter of the sixth book of the
Chemical Arcana by Libavius (for I have not seen it else-
where) that Caesalpinus has written, that it is a remarkable
thing that lead on calcination increases in weight by eight
or ten pounds per cent. Then, seeking the cause, he
says that it is due to the soot which the fire produces
striking the vault of the furnace and by reflection falling
back on the substance. This Caesalpinus would never
have advanced had he paid attention to what I am about
to deduce. Firstly, the soot on being exhaled by the fire
is of so rare a nature, that the seven ounces of increase
found by the sieur Brun would occupy more space than
all the calx he derived from the calcination. In the
second place, this abundance of soot would so blacken
the calx of tin or lead, that the Ladies would never
borrow from it the whiteness of their complexions, as
several do. And again, what would hinder the quantity
of this calx from being infinitely increased, since the fire
42 Rey.
may be continued as long as we wish, and will always
furnish soot ? Let us add that the sieur Brun calcined
his tin on a naked and open fire so that the soot was only
able to pass on one side by the dampers of the furnace
and not to fall on the substance, on which also it could
not descend, not being so heavy as the air contained in
the vessel. As to Libavius, he has rejected this opinion
of Caesalpinus, and even says that apprentices in chemistry
will laugh thereat, without however adducing much against
it: having enveloped his opinion in such a mass of words
that it is not easily extracted from them. Thus he
wishes the following words to pass as a solution of the
doubt: That transmutation alters weight; and a few
lines further on : That burning augments the weight of
lead. Better to see the energy of these replies, it is only
needful to diversify a very little the terms of our ques-
tion, the sense remaining still the same, and adapt them
as follows: Why does the transmutation of lead into
calx change the weight? because, he says, transmutation
changes the weight. Why does burning augment the
weight of lead P because, he says, burning augments the
weight of lead. See I pray you if what he says of the reason
of Caesalpinus is applicable to his own. Assuredly one
needs not to be a great Chemist, or a great Logician withal,
to laugh at it. Receive his reasons who will, they shall
never be accepted by me. But I am ashamed to discover
the shame of this person, whose merit in other respects
is great on account of the number of writings he has
made public, which are filled with much sound doctrine.
ESSAY XX.
That the augmentation of the cala of tin and lead
does not come from the vessel.
I come to opinions which have not been written, at
least as far as I am aware. Since nothing touches the
Essays. 43
tin and lead on calcination except the air and the contain-
ing vessel, those who will not acknowledge the former as
the cause of the increase in weight, cannot I think with
any plausibility have recourse to anything but the latter.
For they might persuade themselves that in the calcina-
tion and incessant agitation of the said metals, the iron
being burnt might become friable on its surface, a portion
of which would mix with the calx and thus increase its
weight. Just as the pearls, which the Pharmacist brays
on his marble acquire a greater weight by the addition
of the stony matter which, being crumbled, mixes with
them; very often to the prejudice of those to whom they
are afterwards given. But in order to rid them of that
opinion, I represent firstly, that if the powdered iron,
which is brown, became mixed to SO great an extent with
the tin, it would darken its calx, which nevertheless is
always white. Secondly, if the vessel were consumed in
this way, it would be useless after two or three calcina-
tions: whereas it lasts for several years, although used
daily. Thirdly, from a very little tin or lead one might
extract the calx in abundance, it being thus easy to reduce
all the vessel to powder by continuation of the fire, which
is contradicted by experiment. What is more, Modestinus
Fachsius has observed (as Libavius reports at the place
already indicated) that in the examination of metals, the
vessel, the cupel, the lead, and the metal examined, are
all heavier after the examination than before exposure to
the fire; although there has been a loss of much matter
dissipated as fumes: which can only happen by the
adhesion to all this of much of the air above-mentioned,
a thing which has hitherto not been comprehended.
So on this account the vessel for the calcination may
be found too heavy, and I beg the sieur Brun to attend
to it. -
44 Rey.
ESSAY XXI.
That it is not the vapours from the charcoal that
augment the weight.
It has been reported to me (I know not if faithfully)
that an intimate friend of mine, a man of profound
knowledge, and of most refined and substantial judg-
ment, to whom the sieur Brun had made the same
request as he made to me, has allowed himself to be
led to the belief that the augmentation of weight in
question proceeds from the vapours of the charcoal,
which passing through the vessel, mingle with the calx.
This I maintain to be impossible. For if such vapours
cannot pass through a beaker of glass, a plate of tin, an
earthen pot (otherwise our broths, sauces, and soups
would be infected with them), how shall they traverse an
iron vessel, the material of which is so much stronger?
If the most subtle air cannot penetrate it (of what use
else would be my AEolipyle?) how shall these gross
vapours penetrate it? and having penetrated it, what
impediments will they find in the calx to be there
arrested P why should they there finish their course?
The heat by its vehemence expels from the tin and the
lead the humidity which bound their particles together,
driving off all the metallic vapours, although these are
natural to them. And it will leave these foreign vapours?
It seems not very probable. O truth, how dear thou art
to me, thus to make me strive against so dear a friend |
ESSAY XXII.
That it is not the volatile salt of the charcoal which
augments the weight.
As soon as I had made a rough sketch of this dis-
course, I sent it to the person of whom I have spoken
in the preceding Essay. A few days thereafter he put
Essays 45
into my own hands a manuscript disavowing the opinion
which I have combatted. And after having opposed to
my belief touching the increase of density and heaviness
of heated air the reasons which I have given in the
twelfth Essay, and refuted in it as well as in the two
Essays following: he puts forth his opinion as I give it
succinctly here. That the augmentation of which we
treat comes necessarily either from the vessel, or from
the air, or else from the charcoal. Not from the vessel,
as it loses nothing of its weight: nor from the air, since
heat can only subtilize it and make it less heavy, as he
presupposes to have shown ; it follows then, he says,
that it is the charcoal to which the augmentation is due.
And to show how that occurs, he says that charcoal
contains two parts or natures, one vegetable, the other
metallic ; and each of these two others, one fixed, the
other volatile. That the fixed part remains at the
bottom of the furnace in the form of ashes, in which
the fixed salt is contained and may be separated by
ablution : and the volatile part ascends all around the
vessel, containing in a superfluous humidity (which is
due to the vegetable part) a volatile salt of metallic
nature, which being raised on the wings of the humidity
and meeting the air directly above the vessel (more
rarefied and less heavy than the vapour which comes
from the charcoal) sinks through it into the vessel, and
attaches itself by a close sympathy to the fixed salt of
the calx of tin, which, having taken up a certain quantity
of it, and being as it were satiated, rejects the surplus:
just as the salt of tartar after a certain number of coho-
bations cannot impregnate itself more with the volatile
salt contained in brandy. Having perused his paper, I
refuted this opinion in his presence by the following
reasons. Since we must believe everyone on the subject
of his own art, if we have nothing to the contrary, it is
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46 Rey.
reasonable that in speaking of the volatile salt we borrow
the language of the Spagyrics, who alone can properly
discourse of it, having discovered it first and revealed it
to us, when we never thought that a volatile salt existed in
nature. They recognise in vegetables (as in almost all
things) two sorts of salt, one fixed, and the other volatile;
the former containing a fixed spirit, and being contained
in the solid parts of its subject; the other containing a
volatile spirit, and being contained in the juices. The
fixed is extracted, so they tell us, by calcination, remain-
ing in the ashes. The other cannot endure fire (being
in fact as in name, volatile), but flies off at the least heat
with the juice containing it: or is lost by the simple
drying up of the vegetable. Now, this being so, it is
beyond doubt, that in charcoal there is no volatile salt
at all; seeing that even in the wood of which it is made
there can be none, since it is dried beforehand: and
even if there were some in it, who does not see that it
would of necessity be lost, when, on heating, the wood is
reduced to charcoal? Indeed, although I admitted un-
justly that charcoal contains some volatile salt, those
who know how rare this salt is in all things, will never be
persuaded that from the small amount of charcoal con-
sumed by the sieur Brun in his calcination, so great a
quantity could have proceeded. For it is not merely
necessary to imagine only seven ounces of it: but also
what replaced the decrease of weight caused by the loss
of vapours from the tin and the aggrandisement of its
volume: and besides what the smoke from the charcoal
Carried elsewhere, not only throughout the laboratory,
but without it, whither the vapours were copiously poured
through its openings. If in these fumes there were
salt in proportion to that which fell into the vessel from
the fumes above it, and the whole were gathered into
one mass, truly the quantity of it would be monstrous.
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Essays. 47
And then, when the calx of tin should have satiated itself
with salt by this imaginary sympathy, what would prevent
the continued heating to deposit more on the top of it,
and fill the vessel, since it descends into it by its proper
heaviness P Experience refutes all this ; and moreover I
have proved that the air above the vessel is so dense that
the salt could not descend in it. In addition, if a furnace
is erected in a wall separating two chambers in such wise
that the vessel is on one side, and the doors and dampers
to introduce charcoal and admit air are on the other, I
maintain that the augmentation will take place, although
no vapours can enter the chamber in which the vessel is
placed. And this I confirm by the experiment which I
made at the iron-works of Jean Rey sieur de la Perro-
tasse, my eldest son, where I found a similar augmenta-
tion with tin which I calcined on a pig, as they call it,
or an ingot of sixteen to twenty hundredweights of iron,
at the moment when, issuing from the furnace, it was
poured into its mould. For no one can say that the
vapours from charcoal had contributed anything here.
Therefore the volatile salt is not admissible in this matter.
ESSAY XXIII.
That the mercurial volatile salt is not the cause of
this augmentation.
Some days after the refutation which I have just
recounted, the same person wrote me another opinion of
his. Namely, that the volatile salt is of mercurial nature,
having no one of the principles in it entirely pure, but
mixed with the others: so that in the salt there is the
true fixed salt, then another less terrestrial, partaking of
the nature of sulphur; then another still more subtle and
penetrating, which partakes of the nature of mercury.
Now, crude cold mercury easily penetrates iron, and
attaches itself closely to it, both internally and exter-
48 Rey.
nally; so that it is not unreasonable to be of opinion that
the volatile salt of mercurial nature, rarefied by fire and
rendered much more penetrating, should succeed in pass-
ing through the thickness of vessels, similarly heated by
the fire and made more easily penetrable, and should
attach itself to the calx of tin by a certain sympathy
which can subsist between them, as well as between gold
and crude mercury. This second opinion is sufficiently
destroyed by the reasons of the preceding Essay; for
having shown that in charcoal there can be no volatile
salt, who does not see it cannot subsist therein in any
fashion ? Again, if this salt of mercurial nature pene-
trate the vessels, it will necessarily dissolve them, and
make of them an amalgam, which does not happen in
our calcination. Besides, crude mercury being exhaled
as we see, has a very small heat; how then can it happen
that this mercurial salt, of so subtle a nature, having
penetrated the vessel should persist in the still burning
calx without swiftly flying off? Again, if we are to find in
each of these principles all three, I do not see why they
cannot all be found in each of these again, and why we
should not go on in this way ad infinitum. These are
speculations subtle indeed, but having no foundation in
nature.
ESSAY XXIV.
That it is not. Aumazality attracted by the ca/v zwhich
augments its zweight. -
Not long since, speaking to a learned and judicious
man, it occurred to me to discover this question to him,
whereupon, having thought a little, he told me his belief
was that the augmentation was due to the fact that the
tin by its great dryness attracted to itself much humidity,
which made it so heavy. But I cannot approve this.
opinion for the reasons that follow. Firstly, because I
Essays. 49
have never learned that a contrary will attract its contrary:
it flees from it rather, or banishes it if it can. Then by
humidity he cannot mean a bare quality, but water or air
endowed with it. As for water, whence would the calx
get it, having none in its neighbourhood? Will there be
found in the laboratory where the calcination is per-
formed, air more humid than the common P Will not the
heat of the furnace have absorbed it P And although
this calx should attract enough water or moist and nebu-
lous air to increase its weight by a fifth or thereby as
experiment proves, we should then have mortar instead
of a dry calx. I will add that at the instant of calcination
the calx has augmented in weight before it has the time
to exercise this imaginary attraction.
ESSAY XXV.
By a single experiment all opinions contrary to mine
are entirely destroyed.
It is said of Hercules that no sooner had he cut off
one of the heads of that Hydra which devastated the
Lernaean marsh, than two others sprang forth. My con-
dition is similar. The error that I combat teems with
opinions, which are so many heads: if I cut off one, we
see two appear. My labour is always on the increase:
and I believe I should never have done if I only employed
myself in cutting off one after the other. To give it the
deathblow, I must gather my strength and make stiff my
arm, in order that I may strike them all off at a single
blow. Let him who will take heed : for now the fatal
stroke will be dealt him. I have just read in Hamerus
Poppius, in the third chapter of his book entitled Basilica
Antimonit the new method which he practises to calcine
antimony. He takes a certain quantity of it, weighs it,
and places it in the fashion of a cone on a slab of marble,
D
5O Rey.
then having a burning mirror, he opposes it to the Sun,
and directs the pyramidal point of the reflected rays on
the point of the cone of antimony, which straightway
fumes abundantly, and in a little while, what the rays
have touched is converted into a very white calx, which
he separates with a knife, and conducts the rays on the
remainder till all has become white: and then the calci-
nation is ended. It is a remarkable thing (he adds) that
although in this calcination the antimony has lost much
of its substance, by the vapours and fumes which are
copiously exhaled, yet its weight augments instead of
diminishing. Now if we seek the cause of this augmen-
tation : will Cardan say that it is the vanishing of the
celestial heat? It is even infused into it more largely by
the solar beams. Will Scaliger say that it is the con-
sumption of the aërated particles P But on being broken
up into calx and increasing in volume, more of these are
thrust into it. Will Caesalpinus allege soot ? There is
no fire to produce any. Would the vessel furnish some-
thing on its part? The rays are conducted so dextrously
on the substance that they do not touch the marble.
Will anyone suggest the vapours of charcoal? None is
used in this affair. As to the volatile salts which have
been so ingeniously brought forward, they here lose their
savour and their charm. Peradventure someone will put
humidity to the fore, as has quite lately been done. But
whence would it come P from the marble? nay nay, that
is not imaginable. From the air P still less, for this
operation should succeed best in the hottest days of
Summer, in the most violent ardours of the Dog-days,
when everything below is so heated, that even in the
shade and in the night-time the air dries soaked linen,
and parches the moist earth. And, during the day,
where the Sun strikes, he burns our complexions, withers
the grass, scorches fruits, desiccates wood, dries up lakes,
Essays. 5 I
lowers rivers, and inflames combustible things like
pigeons' droppings. To seek humidity in the air where-
with to moisten our calx and make it heavier in that
fashion—not by night but in the daytime, not in the
shade but in the Sun, and not where he simply shines
but where his beams gathered in a concave mirror are
reflected with such violence that they melt and calcine
the metals—to seek humidity there, I say, is to seek fire
in ice and a knot in a bulrush, as they say, a thing
which never can be found. Let now all the greatest
minds in the world be fused into one mind, and let this
great mind strain every nerve beyond its power; let him
seek diligently on the earth and in the heavens, let him
Search every nook and cranny of nature: he will only find
the cause of this augmentation in the air when the Sun's
rays heat it, and render it dense and heavy, so that it
then mixes with the calx as the antimony on calcination
crumbles and becomes adherent in its minutest particles.
And this confirms entirely the truth of my belief in the
augmentation of lead and tin : which can have no other
cause than the admixture of condensed air, there being
no difference between the increase of weight in these
two metals and in antimony, only that in the last case the
air is condensed by the solar rays, and in the former by
the heat of the common fire.
ESSAY XXVI.
Why the cala does not increase in weight infimately.
Having thus repulsed contrary opinions, mine alone can
hold the field freely. It is true that perceiving certain.
objections which might encumber its path, I will now go
forward to remove them. The first would seem to lead
us to the absurdity to which I took exception in the case
of Caesalpinus, namely, that my opinion being granted,
the calx of which I treat might increase in weight ad
52 Rey.
infinitum. For why, one will say, should not the calx
increase infinitely, the fire being infinitely continued so
as always to furnish that dense and heavy air to increase
it? I escape this difficulty, which might entangle some
less subtle, by remarking that all matter which is increased
by the addition of another matter is either solid or liquid,
and that the mixing of them may occur in three fashions.
For either the solid matter mixes with solid, or liquid
with liquid, or liquid with solid. The mixing and in-
crease which occurs in the first two cases has no limit.
Mix with this sand and add to it some other sand, and
you will go on increasing it without end. Mix with this
wine and pour into it some other wine, and you never
will have done. It is not the same in the third case,
when a liquid is added to and mixed with a solid: such
a mixed addition will not increase always, will not go on
infinitely. Nature in her inscrutable wisdom has here set
limits which she never oversteps. Mix water with sand
or meal and they will be entirely covered by it, down to
the least of their particles: pour on more, they will not
take it up; and on withdrawing them from the water
they will only carry what adheres to them and suffices
properly to enclose them. Plunge them in again a hun-
dred times and yet again a hundred, they will come out
no better charged; and when left to themselves within
it, they will leave the superfluous water and sink to the
bottom of themselves: so scrupulous is nature to stop at
the limits which she has once prescribed herself. Our
calx is in this condition : “the condensed air becomes
attached to it, and adheres little by little to the smallest
of its particles: thus its weight increases from the begin-
ning to the end : but when all is saturated, it can take
up no more.” Do not continue your calcination in this
hope : you would lose your labour. For the rest, let not
that trouble you which was said in the eleventh Essay,
Essays. 53
namely, that I almost called that air no longer air but an
unnatural air: for these are words of excess, by which I
mean nothing more than that the air has been deprived
of that liquid subtlety which caused it not to adhere to
any substance, and has become gross, heavy, and adherent.
ESSAY XXVII.
Why all other calces and ashes do not increase in
zweight.
I come to another objection which might be raised.
Why do not all other calces and ashes made by the force
of fire increase in weight as well as the calx of tin and of
lead P What privilege have these over the others? ... I
answer that the things calcined or incinerated are of dif-
ferent nature. Some have much exhalable and evapor-
able matter, or (speaking spagyrically) much sulphur and
mercury, which the fire expels to the end. Here there
is much diminution and little ash, which cannot attach
to itself as much of the air condensed by fire as even to
make up for the decrease. Others have little exhalable
and evaporable matter, or little sulphur and mercury :
consequently there is little diminution, much ash (from
the abundance of salt) which attracts so much of the
condensed air, that not only is the diminution made
good, but the weight increases largely in addition.
Stones, vegetables, and animals are usually in the first
named class. Lead and tin in the second. There are
other things which calcination carries to such increase
of volume, that even if little or no matter were lost, the
weight would nevertheless be much diminished, not so
much when examined by aid of the reason as when
examined by the balance. Such are the Indian metal
named Calaem,” and a species of crocus of iron, such as
Chemists can exhibit.
* [Zinc.]
54 Rey.
ESSAY XXVIII.
Whether lead increases in weight as well as tin.
I should have ended, were it not that the sieur Brun
informs me in his letter, that having noticed the augmen-
tation of tin, he made the same experiment with lead,
which he found to diminish by one ounce in the pound:
which sank him still deeper in doubt, having imagined
that the same increase should be there found as with tin,
from the proximity of their nature and from the identity
of the process of calcination. But to the experiment of
the sieur Brun I oppose the experiments of Cardan, of
Scaliger, and notably of Caesalpinus already mentioned,
who says it is worthy of astonishment that lead on
calcination increases in weight by eight to ten pounds in
the hundred. Shall I leave these persons in strife each
to sustain his own experiment P I am too pacific:
behold their reconciliation effected. Some lead is more
pure than others, either because it comes so from the
ores or because it has been previously melted. Those
named above have found augmentation with the pure
lead : the sieur Brun a diminution with the other.
Conclusion.
Behold now this truth, whose brilliance strikes the
eye, which I have drawn from the deepest dungeons of
obscurity. This it is to which the path has been hitherto
inaccessible. This it is which has distressed with toil so
many learned men, who, wishing to know it, have striven
to clear the difficulties which held it encircled. Cardan,
Scaliger, Fachsius, Caesalpinus, Libavius, have curiously
sought it, but never perceived it. Others may be on its
quest, but vainly if they fail to follow the road which I
first of all have made clear and royal : all others being
but thorny footpaths and inextricable byways which lead
never to the goal. The labour has been mine; may the
profit be to the reader, and to God alone the glory.
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