Henry Cavendish (1731-1810)

Experiments on Air

Philosophical Transactions 75, 372 (1785)

In a paper, printed in the last volume of the Philosophical Transactions, in which I gave my
reasons for thinking that the diminution produced in atmospheric air by phlogistication, is not
owing to the generation of fixed air, I said it seemed most likely, that the phlogistication of
air by the electric spark was owing to the burning of some inflammable matter in the
apparatus; and that the fixed air, supposed to be produced in that process, was only
separated from that inflammable matter by the burning. At that time, having made no
experiments on the subject myself, I was obliged to form my opinion from those already
published; but I now find, that though I was right in supposing the phlogistication of the air
does not proceed from phlogiston communicated to it by the electric spark, and that no part
of the air is converted into fixed air; yet that the real cause of the diminution is very
different from what I suspected, and depends on the conversion of phlogisticated air into
nitrous acid.

The apparatus used in making the experiments was as follows: The air through which
the spark was intended to be passed, was confined in a glass tube M, bent to an angle,
as in fig. 4, pl. 1, which, after being filled with quicksilver, was inverted into two glasses of
the same fluid, as in the figure. The air to be tried was then introduced by means of a small
tube, such as is used for thermometers, bent in the manner represented by ABC, fig. 5, the
bent end of which, after being previously filled with quicksilver, was introduced, as in the
figure, under the glass DEF, inverted into water, and filled with the proper kind of air, the
end C of the tube being kept stopped by the finger: then, on removing the finger from C, the
quicksilver in the tube descended in the leg BC, and its place was supplied with air from the
glass DEF. Having thus got the proper quantity of air into the tube ABC, it was held with the
end C uppermost, and stopped with the finger; and the end A, made smaller for that
purpose, being introduced into one end of the bent tube M, fig. 4, the air, on removing the
finger from C, was forced into that tube by the pressure of the quicksilver in the leg BC. By
these means I was enabled to introduce the exact quantity I pleased of any quantity of
soap-lees, or any other liquor which I wanted to be in contact with the air.

In one case however, in which I wanted to introduce air into the tube many times in the
same experiment, I used the apparatus represented in fig. 6, consisting of a tube AB of a
small bore, a ball C, and a tube DE of a larger bore. This apparatus was first filled with
quicksilver; and then the ball C and the tube AB were filled with air, by introducing the end A
under a glass inverted into water, which contained the proper kind of air, and drawing out the
quicksilver from the leg ED by a syphon. After being thus furnished with air, the apparatus
was weighed, and the end A introduced into one end of the tube M, and kept there during the
experiment; the way of forcing air out of this apparatus into the tube being by thrusting
down the tube ED a wooden cylinder of such a size as almost to fill up the whole bore, and by
occasionally pouring quicksilver into the same tube, to supply the place of that pushed into the
ball C. After the experiment was finished, the apparatus was weighed again, which showed
exactly how much air had been forced into the tube M during the whole experiment; it being
equal in bulk to a quantity of quicksilver, whose weight was equal to the increase of weight of
the apparatus.

The bore of the tube M used in most of the following experiments, was about 1/10 of
an inch; and the length of the column of air, occupying the upper part of the tube, was in
general from 1-1/2 to 3/4 of an inch. It is scarcely necessary to inform any one used to
electrical experiments, that in order to force an electrical spark through the tube, it was
necessary, not to make a communication between the tube and the conductor, but to place an
insulated ball at such a distance from the conductor as to receive a spark from it, and to
make a communication between the ball and the quicksilver in one of the glasses, while the
quicksilver in one of the glasses, while the quicksilver in the other glass communicated with
the ground. I now proceed to the experiments.

When the electric spark was made to pass through common air, included between short
columns of a solution of litmus, the solution acquired a red colour, and the air was diminished,
conformably to what was observed by Dr. Priestley. When lime-water was used, instead of
the solution of litmus, and the spark was continued till the air could be no further diminished,
not the least cloud could be perceived in the lime-water; but the air was reduced to 2/3 of
its original bulk; which is a greater diminution than it could have suffered by mere
phlogistication, as that is very little more than 1/6 of the whole. The experiment was next
repeated with some impure dephlogisticated air. The air was very much diminished, but
without the least cloud being produced in the lime-water. Neither was any cloud produced
when fixed air was let up to it; but on the further addition of a little caustic volatile alkali, a
brown sediment was immediately perceived.

Hence we may conclude, that the lime-water was saturated by some acid formed during the
operation; as in the case it is evident that no earth could be precipitated by the fixed air
alone, but that caustic volatile alkali, on being added, would absorb the fixed air, and thus
becoming mild, would immediately precipitate the earth; whereas, if the earth in the
lime-water had not been saturated with an acid, it would have been precipitated by the fixed
air. As to the brown colour of the sediment, it most likely proceeded from some of the
quicksilver having been dissolved. It must be observed, that if any fixed air, as well as acid,
had been generated in these two experiments with the lime-water, a cloud must have been at
first perceived in it, though that cloud would afterwards disappear by the earth being
re-dissolved by the acid; for till the acid produced was sufficient to dissolve the whole of
the earth, some of the remainder would be precipitated by the fixed air; so that we may
safely conclude, that no fixed air was generated in the operation.

When the air is confined by soap-lees, the diminution proceeds rather faster than when it is
confined by lime-water; for which reason, as well as on account of their containing so much
more alkaline matter in proportion to their bulk, soap-lees seemed better adapted for
experiments designed to investigate the nature of this acid, than lime-water. I accordingly
made some experiments to determine what degree of purity the air should be of, in order to
be diminished most readily, and to the greatest degree; and I found that when good
dephlogisticated air was used, the diminution was but small; when perfectly phlogisticated air
was used, no sensible diminution took place; but when 5 parts of pure dephlogisticated air
were mixed with 3 parts of common air, almost the whole of the air was made to disappear.
It must be considered, that common air consists of 1 part of dephlogisticated air, mixed with
4 of phlogisticated; so that a mixture of 5 parts of pure dephlogisticated air, and 3 of
common air, is the same thing as a mixture of 7 parts of dephlogisticated air with 3 of

Having made these previous trials, I introduced into the tube a little soap-lees, and then let
up some dephlogisticated and common air, mixed in the above-mentioned proportion, which
rising to the top of the tube M, divided the soap-lees into its two legs. As fast as the air was
diminished by the electric spark, I continued adding more of the same kind, till no further
diminution took place: after which a little pure dephlogisticated air, and after that a little
common air, were added, in order to see whether the cessation of diminution was not owing to
some imperfection in the proportion of the two kinds of air to each other; but without
effect.[1] The soap-lees being then poured out of the tube, and separated from the
quicksilver, seemed to be perfectly neutralized, as they did not at all discolour paper tinged
with the juice of blue flowers. Being evaporated to dryness, they left a small quantity of salt,
which was evidently nitre, as appeared by the manner in which paper, impregnated with a
solution of it, burned.

For more satisfaction, I tried this experiment over again on a larger scale. About 5 times the
former quantity of soap-lees were now let up into a tube of a larger bore; and a mixture of
dephlogisticated and common air, in the same proportions as before, being introduced by the
apparatus represented in fig. 6, the spark was continued till no more air could be made to
disappear. The liquor, when poured out of the tube, smelled evidently of phlogisticated
nitrous acid, and being evaporated to dryness, yielded 1-4/10 gr. of salt, which is pretty
exactly equal in weight to the nitre which that quantity of soap-lees would have afforded if
saturated with nitrous acid. This salt was found, by the manner in which paper dipped into a
solution of it burned, to be true nitre. It appeared, by the test of terra ponderosa salita, to
contain not more vitriolic acid than the soap-lees themselves contained, which was excessively
little; and there is no reason to think that any other acid entered into it, except the nitrous. A
circumstance however occurred, which at first seemed to show that this salt contained some
marine acid; namely, an evident precipitation took place when a solution of silver was added to
some of it dissolved in water; though the soap-lees used in its formation were perfectly free
from marine acid, and though, to prevent all danger of any precipitate being formed by an
excess of alkali in it, some purified nitrous acid had been added to it, previous to the addition
of the solution of silver. On consideration however I suspected that this precipitation might
arise from the nitrous acid in it being phlogisticated; and therefore I tried whether nitre,
much phlogisticated, would precipitate silver from its solution. For this purpose I exposed
some nitre to the fire, in an earthen retort, till it had yielded a good deal of dephlogisticated
air; and then, having dissolved it in water, and added to it some well purified spirit of nitre
till it was sensibly acid, in order to be certain that the alkali did not predominate, I dropped
into it some solution of silver, which immediately made a very copious precipitate. This solution
however being deprived of some of its phlogiston by evaporation to dryness, and exposure
for a few weeks to the air, lost the property of precipitating silver from its solution; a proof
that this property depended only on its phlogistication, and not on its having absorbed
sea-salt from the retort, or by any other means. Hence it is certain that nitre, when much
phlogisticated, is capable of making a precipitate with a solution of silver; and therefore
there is no reason to think that the precipitate, which our salt occasioned with a solution of
silver, proceeded from any other cause than that of its being phlogisticated; especially as it
appeared by the smell, both on first taking it out of the tube, and on the addition of the spirit
of nitre, previous to dropping in the solution of silver, that the acid in it was much
phlogisticated. This property of phlogisticated nitre is worth the attention of chemists; as
otherwise they may sometimes be led into mistakes, in investigating the presence if marine
acid by a solution of silver.

In the above-mentioned paper I said, that when nitre is detonated with charcoal, the acid is
converted into phlogisticated air; that is, into a substance which, as far as I could perceive,
possesses all the properties of the phlogisticated air of our atmosphere; from which I
concluded, that phlogisticated air is nothing else than nitrous acid united to phlogiston.
According to this conclusion, phlogisticated air ought to be reduced to nitrous acid by being
deprived of its phlogiston. But as dephlogisticated air is only water deprived of phlogiston, it
is plain, that adding dephlogisticated air to a body, is equivalent to depriving it of phlogiston,
and adding water to it; and therefore phlogisticated air ought also to be reduced to nitrous
acid, by being made to unite to, or form a chemical combination with dephlogisticated air; only
the acid formed this way will be more dilute, than if the phlogisticated air was simply
deprived of phlogiston.

This being premised, we may safely conclude, that in the present experiments the
phlogisticated air was enabled, by means of the electrical spark, to unite to, or form a
chemical combination with the dephlogisticated air, and was thus reduced to nitrous acid,
which united to the soap-lees, and formed a solution of nitre; for in these experiments those
two airs actually disappeared, and nitrous acid was actually formed in their stead; and as
moreover it has also been just shown, from other circumstances, that phlogisticated air must
form nitrous acid, when combined with dephlogisticated air, the above-mentioned opinion
seems to be sufficiently established. A further confirmation of it is that, as far as I can
perceive, no diminution of air is produced when the electric spark is passed either through
pure dephlogisticated air, or through perfectly phlogisticated air; which indicates the
necessity of a combination of these two airs to produce the acid. It was also found in the last
experiment, that the quantity of nitre procured was the same that the soap-lees would have
produced if saturated with nitrous acid; which shows that the production of the nitre was not
owing to any decomposition of the soap-lees. It may be worth remarking, that whereas in the
detonation of nitre with inflammable substances, the acid unites to phlogiston, and forms
phlogisticated air, in these experiments the reverse of this process was carried on; namely,
the phlogisticated air united to the dephlogisticated, which is equivalent to being deprived of
its phlogiston, and was reduced to nitrous acid.

In the above-mentioned paper I also gave my reasons for thinking that the small quantity of
nitrous acid, produced by the explosion of dephlogisticated and inflammable air, proceeded
from a portion of phlogisticated air mixed with the dephlogisticated, which I supposed was
deprived of its phlogiston, and turned into nitrous acid, by the action of the dephlogisticated
air on it, assisted by the heat of the explosion. This opinion, as must appear to every one, is
confirmed in a remarkable manner by the foregoing experiments; as from them it is evident
that dephlogisticated air is able to deprive phlogisticated air of its phlogiston, and reduce it
into acid, when assisted by the electric spark; and therefore it is not extraordinary that it
should do so when assisted by the heat of the explosion.

The soap-lees used in the foregoing experiments were made from salt of tartar, prepared
without nitre; and were of such a strength as to yield 1/10 of their weight of nitre when
saturated with nitrous acid. The dephlogisticated air also was prepared without nitre, that
used in the first experiment with the soap-lees being procured from the black powder
formed by the agitation of quicksilver mixed with lead,[2] and that used in the latter from
turbith mineral. In the first experiment, the quantity of soap-lees used was 35 measures,
each of which was equal in bulk to 1 grain of quicksilver; and that of the air absorbed was 416
such measures of phlogisticated air, and 914 of dephlogisticated. In the 2d experiment, 178
measures of soap-lees were used, and they absorbed 1920 of phlogisticated air, and 4860
of dephlogisticated. It must be observed however, that in both experiments some air
remained in the tube uncondensed, whose degree of purity I had no way of trying; so that the
proportion of each species of air absorbed is not known with much exactness.

As far as the experiments hitherto published extend, we scarcely know more of the nature
of the phlogisticated part of our atmosphere, than that it is not diminished by lime-water,
caustic alkalis, or nitrous air; that it is unfit to support fire, or maintain life in animals; and
that its specific gravity is not much less than that of common air; so that, though the nitrous
acid, by being united to phlogiston, is converted into air possessed of these properties, and
consequently, though it was reasonable to suppose that part at least of the phlogisticated air
of the atmosphere consists of this acid united to phlogiston, yet it might fairly be doubted
whether the whole is of this kind, or whether there are not in reality many different
substances confounded together by us under the name of phlogisticated air. I therefore
made an experiment to determine, whether the whole of a given portion of the phlogisticated
air of the atmosphere could be reduced to nitrous acid, or whether there was not a part of a
different nature from the rest, which would refuse to undergo that change. The foregoing
experiments indeed in some measure decided this point, as much the greatest part of the air
let up into the tube lost its elasticity; yet, as some remained unabsorbed, it did not appear
for certain whether that was of the same nature as the rest or not. For this purpose I
diminished a similar mixture of dephlogisticated and common air, in the same manner as
before, till it was reduced to a small part of its original bulk. I then, in order to decompound
as much as I could of the phlogisticated air which remained in the tube, added some
dephlogisticated air to it, and continued the spark till no further diminution took place. Having
by these means condensed as much as I could of the phlogisticated air, I let up some solution
of liver of sulphur to absorb the dephlogisticated air; after which only a small bubble of air
remained unabsorbed, which certainly was not more than 1/120 of the bulk of the
phlogisticated air let up into the tube; so that if there is any part of the phlogisticated air of
our atmosphere which differs from the rest, and cannot be reduced to nitrous acid, we may
safely conclude, that it is not more than 1/120 part of the whole.

The foregoing experiments show that the chief cause of the diminution which common air, or a
mixture of common and dephlogisticated air, suffers by the electric spark, is the conversion
of the air into nitrous acid; but yet it seemed not unlikely, that when any liquor, containing
inflammable matter, was in contact with the air in the tube, some of this matter might be
burnt by the spark, and thereby diminish the air, as I supposed in the above-mentioned paper
to be the case. The best way which occurred to me of discovering whether this happened or
not, was to pass the spark through dephlogisticated air, included between different liquors;
for then, if the diminution proceeded solely from the conversion of air into nitrous acid, it is
plain that, when the dephlogisticated air was perfectly pure, no diminution would take place;
but when it contained any phlogisticated air, all this phlogisticated air, joined to as much of
the dephlogisticated air as must unite to it in order to reduce it into acid, that is, 2 or 3 times
its bulk, would disappear, and no more; so that the whole diminution could not exceed 3 or 4
times the bulk of the phlogisticated air: whereas, if the diminution proceeded from the
burning of the inflammable matter, the purer the dephlogisticated air was, the greater and
quicker would be the diminution. The result of the experiments was, that when
dephlogisticated air, containing only 1/20 of its bulk of phlogisticated air, that being the
purest air I then had, was confined between short columns of soap-lees, and the spark
passed through it till no further diminution could be perceived, the air lost 43/200 of its
bulk; which is not a greater diminution than might very likely proceed from the
first-mentioned cause; as the dephlogisticated air might easily be mixed with a little common
air while introducing into the tube.

When the same dephlogisticated air was confined between columns of distilled water, the
diminution was rather greater than before, and a white powder was formed on the surface
of the quicksilver beneath; the reason of which probably was, that the acid produced in the
operation corroded the quicksilver, and formed the white powder; and that the nitrous air,
produced by that corrosion, united to the dephlogisticated air, and caused a greater
diminution than would otherwise have taken place. When a solution of litmus was used, instead
of distilled water, the solution soon acquired a red colour, which became paler and paler as
the spark was continued. When lime-water was let up into the tube, a cloud was formed, and
the air was further diminished by about 1/5. The remaining air was good dephlogisticated air.
In this experiment therefore the litmus was, if not burnt, at least decompounded, so as to
lose entirely its purple colour, and to yield fixed air; so that, though soap-lees cannot be
decompounded by the process, yet the solution of litmus can, and so very likely might the
solutions of many other combustible substances. But there is nothing, in any of these
experiments, which favours the opinion of the air being at all diminished by means of
phlogiston communicated to it by the electric spark.

[1] From what follows it appears, that the reason why the air ceased to diminish was, that as
the soap-lees were then become neutralized, no alkali remained to absorb the acid formed
by the operation, and in consequence scarce any air was turned into acid. The spark however
was not continued long enough after the apparent cessation of diminution, to determine with
certainty, whether it was only that the diminution went on remarkably slower than before, or
that it was almost come to a stand, and could not have been carried much further, though I
had persisted in passing the sparks.

[2] This air was as pure as any that can be procured by most processes. I propose giving an
account of the experiment, in which it was prepared, in a future paper.




Georg Ernst Stahl (1660-1734)


extract from


Zymotechnia fundamentalis ...


Halle, 1697 [from Henry Marshall Leicester and Herbert S. Klickstein, A Source Book in

Chemistry 1400-1900 (New York: McGraw Hill, 1952)]


The same thing works very well with sulfur, when certainly two parts, or better, three parts

of alkali salt and one of pulverized sulfur are successively poured into and fused in a

crucible. There is formed liver of sulfur. This, in the space of a quarter of an hour more or

less, by fire alone, without any addition, can be converted to such a salt as is obtained from

oil of sulfur per campanum and salt of tartar, that which is commonly called vitriolated

tartar. There is no more trace of sulfur or alkali salt, and in place of the red color of the

liver, this salt is most white; in place of the very evil taste of the liver, this salt is very

bitter; in place of the easy solution, nay, the spontaneous deliquescence of the liver, by

reason of its alkali salt, this salt is the most difficult of all salts except tartar of wine to be

dissolved; in place of the impossibility of crystallizing the liver, this is very prone to form

almost octahedral crystals; in place of the fusibility of the liver, this is devoid of all fusion.


If this new salt, from the acid of sulfur and alkaline salt formed as stated above when the

phlogiston has been used up, is treated with charcoal, in the space of a quarter of an hour the

original liver of sulfur reappears, and this can be so converted a hundred times. ...


I can indeed show by various other experiments how phlogiston from fatty substances and

charcoal enters very promptly into metals themselves and regenerates them from the

burned calx into their own fusible, malleable, and amalgamable state.





extract from


Zufällige Gedanken und nützliche Bedencken ...


Halle, 1718 [from Henry Marshall Leicester and Herbert S. Klickstein, A Source Book in

Chemistry 1400-1900 (New York: McGraw Hill, 1952)]


Now the first thing to consider concerning the principle of sulfur is its properties, as follows:


  1.Behavior toward fire

  2.Display of colors

  3.Subtle and intimate mixing with other metal substances

  4.Behavior toward water and humidity

  5.Its own great and wonderful subtlety

  6.Its own form in the dry or fluid state

  7.Where it can be found or occurs


According to these conditions and intentions, I now have demonstrable grounds to say, first,


Toward fire, this sulfur principle behaves in such a manner that it is not only suitable for the

movement of fire but is also one and the same being, yes, even created and designed for it.


But also, according to a reasonable manner of speaking, it is the corporeal fire, the essential

fire material, the true basis of fire movement in all inflammable compounds.


However, except in compounds, no fire at all occurs, but it dissipates and volatilizes in

invisible particles, or at least, develops and forms a finely divided and invisible fire, namely,



On the other hand, it is very important to note that this fire material, of and by itself and

apart from other things, especially air and water, is not found united and active, either as a

liquid or in an attenuated state. But if once by the movement of fire, with the addition of free

air, it is attenuated and volatilized, then by this in all such conditions it is lost through

unrecognizable subtlety and immeasurable attenuation, so that from this point on no science

known to man, no human art, can collect it together or bring it into narrow limits, especially if

this occurred rapidly and in quantity.


But how enormously attenuated and subtle material becomes through the movement of fire is

shown by experience, which furnishes a field for thought and which also delights us.


From all these various conditions, therefore, I have believed that it should be given a name,

as the first, unique, basic, inflammable principle. But since it cannot, until this hour, be found

by itself, outside of all compounds and unions with other materials, and so there are no

grounds or basis for giving a descriptive name based on properties, I have felt that it is most

fitting to name it from its general action, which it customarily shows in all its compounds. And

therefore I have chosen the Greek name phlogiston, in German, Brennlich. ...


The seventh and last consideration was where it could be found or occurred. The answer to

this is now also in part easy to give from the discussion already presented, and from

consideration that all corporeal compounded things have more or less of this substance, in all

the so-called "kingdoms": vegetable, animal, and mineral. As then in the first two kingdoms

there is contained a great amount of this principle, and all their parts are intimately

penetrated and combined with it (except the watery parts which occur in them, but which still

are not entirely free from it as long as they are in the body), then it is chiefly found in the

fatty materials of both kingdoms.


In the mineral kingdom there is nothing but water, common salt, pure vitriolic salts, and light

sand and stones in which the substance is little or not at all found. On the other hand, coal and

bitumen are full of it; sulfur, not indeed in weight, but in the number of its finest particles, is

completely possessed with it. Not less is it found in all inflammable, incomplete, and so-called

"unripe" metals.





extract from


Fundamenta chymiae ...


Norimbergae, 1723 [translated by Peter Shaw (1730), from Henry Marshall Leicester and

Herbert S. Klickstein, A Source Book in Chemistry 1400-1900 (New York: McGraw Hill,





  1.Universal chemistry is the Art of resolving mixt, compound, or aggregate Bodies into

    their Principles; and of composing such Bodies from those Principles.

  2.It has for its Subject all the mix'd, compound, and aggregate Bodies that are

    resolvable and combinable; and Resolution and Combination, or Destruction and

    Generation, for its Object.

  3.Its Means in general are either remote or immediate; that is, either Instruments or the

    Operations themselves.

  4.Its End is either philosophical and theoretical; or medicinal, mechanical, economical, and


  5.Its efficient Cause is the Chemist.




The Structure of Simple, Mix'd, Compound and Aggregate Matter


  1.As mix'd, compound, and aggregate Bodies are, according to our Definition, the Subject

    of Chemistry, 'tis necessary that we here consider their chemical Structure.

  2.All natural Bodies are either simple or compounded: the simple do not consist of physical

    parts; but the compounded do. The simple are Principles, or the first material causes of

    Mixts; and the compounded, according to the difference of their mixture, are either

    mix'd, compound or aggregate: mix'd, if composed merely of Principles; compound, if

    formed of Mixts into any determinable single thing; and aggregate, when several such

    things form any other entire parcel of matter, whatsover it be.

  3.A Principle is defined, à priori, that in mix'd matter, which first existed; and à

    posteriori, that into which it is at last resolved.

  4.Both these definitions are exact, if we allow of a pure, natural resolution: but as this is

    not easily obtainable from the Chemistry of these days, and so can hardly be come at by

    Art, a difference, at present, prevails between the physical and chemical Principles of

    mix'd Bodies.

  5.Those are called physical Principles whereof a Mixt is really composed, but they are not

    hitherto settled: for the four Peripatetical Elements, according to their vulgar

    acceptation, do not deserve this title. And those are usually termed chemical Principles,

    into which all Bodies are found reducible by the chemical operations hitherto known.

  6.These chemical Principles are called Salt, Sulphur, and Mercury; the analogy being taken

    from Minerals: or, Salt, Oil, and Spirit; to which Dr. Willis adds Phlegm and Earth; but

    improperly, since Phlegm is comprehended under Spirit: for inflammible Spirits cannot

    be here meant; these consisting manifestly of Water, Oil and Salt, as we shall see


  7.But as the four Peripatetic Elements, howsoever understood, cannot have place, if

    supposed specifically the same in all Subjects; so neither can the Chemical Principles: for

    no-one has hitherto pretended to shew that these Principles are specifically the same in

    all Bodies. But if consider'd only as to their generical qualities, they may be allow'd in


  8.We say particularly in Compounds, because all the darkness and disputes about

    Principles arise from a neglect of that real distinction between original and secondary

    Mixts, or Mixts consisting of Principles and Bodies compounded of Mixts. Whilst these

    two are confounded, and supposed to be resolved by an operation that is contrary to

    Nature, the common chemical Principles of vegetables, animals and minerals are

    produced, and prove in reality artificial Mixts: but when Compounds are separated by

    bare resolution, without the least combination, their Principles are natural Mixts.

  9.By justly distinguishing between Mixts and Compounds, without directly undertaking to

    exhibit the first Principles of the latter, we may easily settle this affair. Helmont and

    Becher have attempted it; the former taking Water for the first and only material

    Principle of all things; and the other, Water and Earth; but distinguishing the Earth into

    three kinds.