precipitate, treated in the same way behaved similarly. In this case I
obtained a pure fire-air, without any aerial acid in it.
+41. Eighth Experiment.+--I have proved, in a treatise on arsenic
communicated to the Royal Swedish Academy of Sciences, that this
poisonous substance is compounded of a peculiar acid and an inflammable
substance. I also shewed in the same treatise how this acid can be
sublimed into ordinary arsenic simply by continued heat; and although I
clearly perceived the reason for this, even at that time, still I was
unwilling to mention it there in order to avoid prolixity. I placed some
of this fixed acid of arsenic in a small retort with a bladder attached,
for distillation. When the acid had gone into fusion, and glowed
brightly, it began to boil; during this ebullition arsenic rose into the
neck and the bladder became expanded; I continued with this heat as long
as the retort would hold out. The air collected was likewise fire-air.
In the same treatise I made mention of a peculiar explosion which took
place in the distillation of zinc with the acid of arsenic. How clear,
how manifest does the explanation of this phenomenon not become when one
is satisfied that in this case fire-air is present in the retort in its
greatest purity, and the zinc is in red hot fusion? What more is
necessary for its ignition?
I have very often regarded with pleasure the brightly glowing sparks
which are produced in a retort by heat alone, during the reduction of
metallic calces, when only a very little coal dust is mixed along with
it.
We shall now see whether this fire-air is not the same air which had
been lost without fire (Sec.Sec. 8-15), and with fire (Sec.Sec. 17-23).
+42. First Experiment.+--I filled a bottle which was capable of holding
16 ounces of water with pure fire-air according to the method which is
described in Sec. 30, letter e. I placed the bottle, inverted, in a glass
which was filled with a solution of liver of sulphur. The solution rose
a little into the bottle hour by hour, and after the lapse of 2 days the
bottle was filled with it.
+43. Second Experiment.+--I mixed in a bottle 14 parts of that air from
which the fire-air had been removed by liver of sulphur (Sec. 8), and which
I have called vitiated air (Sec. 29), with 4 parts of our fire-air, and
placed the bottle, inverted and open, in a vessel which was also filled
with a solution of liver of sulphur. After 14 days the 4 parts of
fire-air were lost, and the solution had risen into their place.
+44. Third Experiment.+--After I had filled a bottle with our air, I
poured some colourless animal oil into it and closed it tightly. After a
few hours it had already become brown, and by the next day black. It is
no small inconvenience to preserve this oil white in apothecaries'
shops. It is found necessary to pour this oil into small phials, and to
preserve it most carefully from the access of air. When such a
colourless oil is mixed with any acid, the acid, as well as the oil,
becomes black even in an hour, although it has been diluted with water.
Even vinegar has the same effect. There is no other reason, therefore,
why the oil becomes at once black in the air, than that the fire-air
present in the air deprives it of its phlogiston, and thereby develops a
subtle acid, previously united with this phlogiston, which produces the
blackness.
+45. Fourth Experiment.+--(_a._) Into a bottle of 7 ounces, which was
filled with fire-air, I put a piece of phosphorus from urine and closed
it with a cork. I then heated, by means of a burning candle, the place
where the phosphorus lay; the phosphorus took fire with very great
brilliancy. As soon as the flame had gone out, the bottle broke into
fragments.
(_b._) As the bottle in the foregoing experiment was very thin, I
repeated it with a somewhat thicker bottle, and after everything had
become cold I wanted to take the cork out of the bottle under water. It
was not possible for me to do this, however, so tightly did the
external air press the cork into the bottle. Accordingly I forced it
inside the bottle; thereupon water entered the bottle and filled it
almost completely. Since the first bottle was only very thin, the reason
that it was crushed must be ascribed to the external air.
(_c._) When I mixed vitiated air with one third of fire-air, and burned
a piece of phosphorus in the mixture, only 1/3 of it was absorbed.
+46. Fifth Experiment.+--I also repeated the same experiment which is
described in Sec. 19, only with this difference that I took the tube
longer, and filled the flask with my fire-air. It was pleasing to
observe how the water rose gradually into the flask; and how the flame
went out when 7/8 of the flask were full of water.
+47. Sixth Experiment.+--I laid some glowing coals upon the stand (Sec. 21,
letter _c_), and placed over them a flask which was filled with
fire-air. The coals had not even reached the air in the flask before
they began to burn very brilliantly.
After everything had become cold, I made an aperture under the flask,
whereupon the fourth part became filled with water. But when I removed,
by means of milk of lime, the aerial acid which was present in the
residual air (Sec. 22) there remained in the flask only the fourth part. In
this air a candle could still burn.
+48. Seventh Experiment.+--I also examined the behaviour of fire-air
with sulphur (Sec. 23). As soon as the burning sulphur came into contact
with the fire-air contained in the flask, the flame became much larger
and brighter. When this fire had gone out, the water in the dish had
found a way to come through the mass into the flask, which became 3/4
filled with it. As I employed for these last 3 experiments a flask which
was only of 30 ounces measure, I was obliged to arrange the stand (Sec. 21)
to suit.
+49.+ I have mentioned (Sec. 16) that I found vitiated air lighter than
ordinary air. Must it not follow from this that the fire-air is heavier
than our air? As a matter of fact, I actually found, when I accurately
weighed as much fire-air as occupied the space of 20 ounces of water,
that this was almost 2 grains heavier than the same bulk of common air.
+50.+ These experiments shew, therefore, that this fire-air is just that
air by means of which fire burns in common air; only it is there mixed
with a kind of air which seems to possess no attraction at all for the
inflammable substance, and this it is which places some hindrance in the
way of the otherwise rapid and violent inflammation. And in fact, if air
consisted of nothing but fire-air, water would surely render small
service in extinguishing outbreaks of fire. Aerial acid mixed with this
fire-air, has the same effect as vitiated air. I mixed one part of
fire-air with 4 parts of aerial acid; in this mixture a candle still
burned moderately well. The heat which lurks in the small interstices of
the inflammable substance cannot possibly make up so much heat as is
felt in fire; and I think I am not mistaken when I conclude from my
experiments that the heat is really brought forth and produced in the
first place from fire-air and the phlogiston of the inflammable
substance....
* * * * *
+80.+ I had long wished to have some of the precipitate of mercury _per
se_, in order to see whether it also would yield fire-air during
reduction by means of heat alone. At length I obtained some from my much
esteemed friend Doctor Gahn. This so-called precipitate had the
appearance of small dark-red crystals resembling cinnabar. Now, as I
know that mercury cannot be dissolved in muriatic acid unless it has
lost its phlogiston, which takes place during its solution in acid of
nitre or in vitriolic acid; and as this is also the reason why nitre
must be present in a mixture of calcined vitriol, common salt, and
quicksilver, I therefore poured muriatic acid upon a part of this red
precipitate; the solution was soon formed and was somewhat hot; I
evaporated it to dryness and increased the heat. Everything sublimed,
and a true corrosive sublimate was formed. Hence this precipitate,
produced by heat alone, is a calcined mercury. I then placed the other
part of this precipitate over the fire in a small glass retort to which
I had fastened an empty bladder. As soon as the retort became red hot
the bladder became expanded, and at the same time the reduced mercury
rose into the neck. In this case no red sublimate arose as customarily
takes place with that calx which is prepared by the acid of nitre. The
air obtained was a pure fire-air. This is a remarkable circumstance,
that the fire-air which had previously removed from the mercury its
phlogiston in a slow calcination, gives this same phlogiston up to it
again when the calx is simply made red-hot. Still we have several such
phenomena, where heat similarly alters the attractive forces between
substances.
* * * * *
+83. Air is a Dulcified Elastic Acid.+
In the foregoing experiments I have demonstrated the two proximate
constituents of common air, because it was not necessary to know
anything more about it for a clear knowledge of fire. I shall now go
further, and see whether a still deeper decompounding of air is
possible.
+First Experiment.+--I placed a rat in a flask capable of holding 4
quarts of water; I gave it some bread softened in milk and closed the
flask with a wet bladder. It died 31 hours afterwards. I then held the
flask, inverted, under water and made a hole in the bladder, when two
ounces of water rose into it. This small diminution of the air was
probably caused by the heat which the rat took with it, which had
previously driven the air out.
+84. Second Experiment.+--I took a large soft bladder and fastened a
tube into its opening; then I filled it with the air out of my lungs,
and held the tube and bladder with my right hand and closed my nostrils
with the left. I respired the air as long as I could, and was able to
make 24 inspirations (regarding which it is to be observed that at the
last I was obliged to draw the whole bladder full of air into my lungs
at once, while at the beginning only the half of it was necessary). I
then closed the tube with my finger, and tied up the bladder. This air
had properties similar to the preceding in which the rat died. That is
to say, it contained one-thirtieth part of aerial acid, which I
separated from it by milk of lime; and a burning candle at once went out
in it.
+85. Third Experiment.+--I placed a few flies in a bottle into which I
had put some honey smeared upon paper. After a few days they had died.
They likewise had not absorbed any air; milk of lime, however,
diminished this air about one fourth part, and the remainder
extinguished fire.
I then took a bottle of 20 ounces measure and bored a hole in the bottom
of it with the corner of a broken file (Fig. 5, A). Into this bottle I
put a small piece of unslaked lime, and closed the mouth with a cork
through which I had previously fixed a tube B. Round about this cork I
placed a ring of pitch, and placed over it an inverted glass C, into
which I had previously put a large bee and had given it some honey which
was smeared upon paper; but in order that no air could penetrate within
the ring of pitch, I pressed the glass firmly in; I afterwards placed
the bottle in the dish D, into which I poured so much water that it was
half immersed in it; as soon I observed that the bottle was raised by
the water, I put a small weight upon the glass. The water rose a little
into the bottle every day through the opening A; and I also shook the
bottle a little sometimes in order that the skin which formed over the
milk of lime might break. After the lapse of seven days the water had
risen to E, and the bee was dead. Occasionally I put 2 bees into the
glass C, when just as much air was converted into aerial acid in half
the time. Caterpillars and butterflies behaved in exactly the same way.
+86. Fourth Experiment.+--I placed some peas in a small flask, which was
capable of holding 24 ounces of water, and poured so much water upon
them that they were half covered with it; I then closed the flask. The
peas began to strike roots, and grew up. As I found after 14 days that
they would not increase further, I opened the flask, inverted, under
water, and found the air neither increased nor diminished. The fourth
part, however, was absorbed by milk of lime, and the remaining air
extinguished flame. I kept fresh roots, fruits, herbs, flowers, and
leaves, each by itself, in the flask, and after a few days I likewise
observed the fourth part of the air converted into aerial acid. If flies
are placed in such air they die immediately.
+87.+ These are accordingly strange circumstances, that the air is not
noticeably absorbed by animals endowed with lungs, contains in it very
little aerial acid, and yet extinguishes fire. On the other hand insects
and plants alter the air in exactly the same way, but still they convert
the fourth part of it into aerial acid. Accordingly I was curious to
know whether the fire-air was not that which was here converted into
aerial acid, because in these latter experiments just as much of the air
was converted into aerial acid as there was of fire-air present in it.
+88. Fifth Experiment.+--In a bottle of 20 ounces capacity, I mixed one
part of fire-air with 3 parts of the preceding air in which peas would
not any longer grow, and from which the aerial acid was separated. (That
is to say, I filled the bottle with water, and placed 4 peas in it; I
then allowed one fourth of the water to run into the bladder in which
fire-air was contained, and the remainder into another bladder in which
this vitiated air was contained (Sec. 30, _g._), while I took care that the
peas did not fall into the bladder. I also left so much water behind,
that the peas were half covered with it.) Here also I observed the peas
growing up, and after they would not increase any more I found this air
likewise not absorbed, but almost the fourth part was absorbed by milk
of lime. Hence it is the fire-air which is here converted into aerial
acid. In 3 parts of aerial acid and one part of fire-air peas do not
grow. I mixed vitiated air (Sec. 20) with fire-air which behaved in just
the same way: that is to say the fire-air was converted into aerial
acid.
+89. Sixth Experiment.+--I mixed, in the same proportions, fire-air and
air vitiated by peas, and filled a bladder with it. Then when I had
completely exhaled the air present in my lungs, I respired this newly
compounded air as many times as possible. I then found that it contained
very little aerial acid in it, and when this was separated from it, it
extinguished fire. I believe that one must ascribe to the blood present
in the pulmonary veins, the effect which animals endowed with lungs have
upon the air. The following experiment gives me cause for this.
It is known that freshly drawn blood, when it stands in the open air,
assumes a fine red on the surface, and that the under portions likewise
become red when they come into contact with the air. Does the air in
this case undergo any alteration? I filled a flask one third part with
freshly drawn ox blood, closed it tightly with a bladder, and shook up
the blood frequently. Eight hours afterwards I neither found aerial acid
in this air, nor that its bulk was diminished; but the flame of a candle
was immediately extinguished in it. I made this experiment in winter
time, from which may be gathered that the effect cannot be ascribed to
any putrefaction, for this blood was found still fresh 6 days
afterwards, and besides, all putrefactions produce aerial acid. I was
now curious to know how fire-air by itself would behave with animals and
plants.
+90. Seventh Experiment.+--(_a._) I put 2 ounces of nitre into a small
glass retort upon glowing coals, and attached a large bladder softened
with water (Sec. 35), and allowed the nitre to boil until I had received
3/4 of a quart of fire-air in the bladder. I then tied up the bladder
and separated it from the retort; I then placed a tube in its opening,
and after I had completely emptied my lungs, I began to respire air from
this bladder (Sec. 84). This proceeded very well, and I was able to make 40
inspirations before it became difficult for me; eventually I expelled
the air again from my lungs as completely as possible. It did not seem
to have diminished particularly, and when I filled a bottle with it and
introduced a burning candle, this still burned. I then began to respire
this air anew, and was able to make 16 more inspirations. It now
extinguished the flame, but I found only some traces of aerial acid in
it. (_b._) I was surprised that I was not able the first time to take
away from this air the property of allowing fire to burn in it; I
thought that perhaps the great humidity prevented me from drawing this
air into my lungs so often as was really possible. Accordingly I
repeated the same experiment, only with this difference, that I put a
handful of potashes into the bladder before the fire-air was driven into
it. I then began to draw this air into my lungs, and counted 65
inspirations before I was compelled to desist. But when I lowered a
burning candle into this air, it still burned well, although only for a
few seconds.
+91. Eighth Experiment.+--I closed the hole in the bottle at A (Fig. 5)
with a cork, as also the tube B, and then filled the bottle with
fire-air (Sec. 30, _e._). Then I had at hand the glass C, in which I had
placed 2 large bees, and had provided some honey for their stay. I
opened the stopped-up tube, placed this glass over it as quickly as
possible, and pressed it into the ring of pitch. I afterwards placed the
whole in the dish D, which I had filled with milk of lime, and withdrew
the cork at A. In this case I observed the milk of lime to rise a little
into the bottle every day, and after 8 days had elapsed the bottle was
almost completely filled with it, and the bees were dead.
+92. Ninth Experiment.+--Plants, however, will not grow noticeably in
pure fire-air. I filled with this air a bottle capable of holding 16
ounces of water, and which contained 4 peas (Sec. 88). They got roots, but
did not grow up at all; with milk of lime the twelfth part was absorbed.
I then filled this air into another bottle which also contained 4 peas.
After 14 days they had got roots, but also did not grow up, and with
milk of lime likewise only the twelfth part was absorbed. I repeated
this experiment 3 times more with the same air, and it was observed that
the fourth and fifth times the peas had grown upwards a little. There
still remained one-half of the whole air, and in this fire could still
burn. There is no doubt that the whole quantity of fire-air could have
been converted into aerial acid if I had continued the operation longer.
It may also be observed that the peas act more strongly upon the
fire-air when they send out roots than subsequently.
+93.+ Hence it is the fire-air by means of which the circulation of the
blood and of the juices in animals and plants is so fully maintained.
Still it is a peculiar circumstance that blood and the lungs have not
such action upon fire-air as insects and plants have, for the latter
convert it into aerial acid, and the former into vitiated air (Sec.Sec. 29,
89, 90). It is not so easy to furnish the reason for this, yet I will
risk it. It is known that the acids lose those properties by which they
reveal themselves as acids, by the addition of the inflammable
substance, as sulphur, the elastic acid of nitre, regulus of arsenic,
sugar, and the like, plainly shew. I am inclined to believe that
fire-air consists of a subtle acid substance united with phlogiston, and
it is probable that all acids derive their origin from fire-air. Now, if
this air penetrates into plants, these must attract the phlogiston, and
consequently the acid, which manifests itself as aerial acid, must be
produced. This they again give up. The objection that so great a
quantity of aerial acid is nevertheless obtained in the destruction of
plants, and that, consequently, these must attract the aerial acid, has
no weight, since otherwise the air in my vessels in which the peas were
contained must have become for the most part lost, which, however, did
not take place.... If plants abstract the phlogiston from the air, the
aerial acid must be lighter. But experiment shows me the opposite; I
found it, after careful weighing, somewhat heavier, but this is not
contrary to my opinion; as it is known that all acids retain water
strongly, the aerial acid must possess the same property, and this may
consequently cause the most of the weight. If all this is accurate,
another question then arises: Why do not blood and the lungs likewise
convert fire-air into such an aerial acid? I take the liberty here also
of giving my opinion of this, for how would all these laboriously
executed experiments help me if I had not the hope of coming by means
of them nearer to my ultimate object, the truth? Phlogiston, which makes
most substances with which it unites liquid as well as mobile and
elastic, must have the same effect upon blood. The globules of blood
must attract it from the air through the small pores of the lungs. By
this union they become separated from one another, and are consequently
made more liquid. They then appear bright red (Sec. 89). They must,
however, give this attracted phlogiston up again during the circulation,
and in consequence, be placed in a condition to absorb the inflammable
substance anew from the air at that place where they are in the most
intimate contact with it, that is, in the lungs. Where this phlogiston
has gone to during the circulation of the blood, I leave to others to
ascertain. The attraction which the blood has for phlogiston cannot be
so strong as that with which plants and insects attract it from the air,
and then the blood cannot convert air into aerial acid; still it becomes
converted into an air which lies midway between fire-air and aerial
acid, that is, a vitiated air; for it unites neither with lime nor with
water after the manner of fire-air and it extinguishes fire, after that
of aerial acid. But that the blood really attracts the inflammable
substance I have additional experiment to prove, since I have removed
phlogiston by help of my lungs from inflammable air, and have converted
this into vitiated air.
I filled a bladder with the air which one obtains from iron filings and
vitriolic acid (Sec. 30, _c._), and respired it in the manner previously
described (Sec. 84). I was only able to inhale it 20 times, and after I had
somewhat recovered, I expelled the air once more from my lungs as
completely as possible, and again inhaled this inflammable air: after 10
inhalations I was compelled to desist from it, and observed that it
could no longer be kindled, and also would not unite with lime water.
In one word it was a vitiated air.