Read Ebook: Discovery of Oxygen Part 2 by Scheele Carl Wilhelm

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+29.+ I took a glass retort which was capable of holding 8 ounces of water, and distilled fuming acid of nitre according to the usual method. In the beginning the acid went over red, then it became colourless, and finally all became red again; as soon as I perceived the latter, I took away the receiver and tied on a bladder, emptied of air, into which I poured some thick milk of lime in order to prevent the corrosion of the bladder. I then proceeded with the distillation. The bladder began to expand gradually. After this I permitted everything to cool, and tied up the bladder. Lastly I removed it from the neck of the retort. I filled a bottle, which contained 10 ounces of water, with this gas , I then placed a small lighted candle in it; scarcely had this been done when the candle began to burn with a large flame, whereby it gave out such a bright light that it was sufficient to dazzle the eyes. I mixed one part of this air with three parts of that kind of air in which fire would not burn; I had here an air which was like the ordinary air in every respect. Since this air is necessarily required for the origination of fire, and makes up about the third part of our common air, I shall call it after this, for the sake of shortness, Fire-air; but the other air which is not in the least serviceable for the fiery phenomenon, and makes up about two-thirds of our air, I shall designate after this with the name already known, of Vitiated Air.

+30.+ Anyone might ask me in what way I bring air from one vessel into another. I find it necessary therefore to describe this in the first place. My arrangements and vessels are the very simplest that one can possibly have: flasks, retorts, bottles, glasses, and ox bladders are the things which I employ. The bladders, while they are still fresh, are rubbed, and blown up very fully, then tightly tied and hung up to dry. When I wish to use such a bladder and find it blown up just as fully as at first, I am thereby assured that it is tight.

These are the methods which I employed in my investigations of air. I admit that they will not particularly please some, because they do not decide with great exactness. They afforded me satisfaction, however, in all my investigations; and people will often split a hair where it is not in the least necessary.

+31. Continuation of the Experiment mentioned in ? 29+ ...

Anyone might object and say that the air obtained according to ? 29 is perhaps nothing else than a dry acid of nitre converted into elastic vapours. But if this opinion had any foundation, this air should not only be corrosive, but should also produce nitre anew with alkalies. This, however, does not occur. Nevertheless, this objection would possess considerable weight were I not able to prove that several substances produce the same air as the acid of nitre does during distillation. But proof of this is not wanting.

I have proved in a treatise on manganese, which is to be found in the Transactions of the Royal Swedish Academy of Sciences for the year 1774, that this mineral is not soluble in any acid unless an inflammable substance be added, which communicates the phlogiston to the manganese, and by this means effects an entrance of the latter into the acids. I have shown in the same place that vitriolic acid, nevertheless, during a strong distillation with powdered manganese, unites with it and makes it soluble in water; and if this manganese is separated again from the vitriolic acid by means of precipitating agents, there are found in it the most distinct traces of the inflammable substance.... I had already observed a few years ago, that if in the calcination of manganese with oil of vitriol in an open crucible, some coal dust was driven by the current of air over the surface of this mixture, these fine coals took fire in the same instant with very great brilliancy. I accordingly made the following experiments.

+32. First Experiment.+--I mixed so much concentrated oil of vitriol with finely powdered manganese that it became a stiff magma. I distilled this mixture from a small retort on the open fire. In place of a receiver I made use of a bladder, empty of air, and, in order that the vapours which might pass over should not attack the bladder, I poured into it some milk of lime . As soon as the bottom of the retort became red hot, an air passed over which gradually expanded the bladder. This air had all the properties of a pure fire-air.

+33. Second Experiment.+--When I distilled two parts of finely pulverised manganese with one part of the phosphorous acid of urine in the same way as is indicated in the preceding paragraph, I likewise obtained fire-air.

It is thus seen constantly that the acid of nitre goes off again blood-red when separated by means of heat from the metals which had been dissolved in this menstruum.

I distilled mercurial nitre in the foregoing manner until the acid of nitre had separated from the residual red precipitate. In this case also I obtained our fire-air.... Whence comes the boiling of nitre, fused in a crucible and obscurely red-hot? Neither smoke nor vapours are seen to rise from it, and yet coal dust flying above the open crucible takes fire, burning brilliantly. Whence comes it that such nitre maintained in red-hot fusion in a glass retort for half an hour, becomes moist in open air and deliquesces after cooling, and still does not show any trace of alkali? What is the reason that this liquefied nitre permits its volatile acid to escape immediately, when rubbed or mixed with the vegetable acids?... If the chemists of the preceding century had thought worthy of a more particular examination, the elastic fluids resembling air which manifest themselves in so many operations, how advanced should we now be! They desired to see everything in corporeal form, and to collect everything as drops in the receiver. This is now for the first time better inquired into, and the air has begun to be carefully examined: and who is there who does not perceive the advantage which the results of such experiments carry with them?

+35. Fourth Experiment.+--I put an ounce of purified nitre into a glass retort for distillation and made use of a bladder, moistened and emptied of air, in place of a receiver . As soon as the nitre began to glow it also began to boil, and at the same time the bladder was expanded by the air that passed over. I proceeded with the distillation until the boiling in the retort ceased, and the nitre was about to force its way through the softened retort. I obtained in the bladder the pure fire-air which occupied the space of 50 ounces of water. This is the cheapest and best method of obtaining fire-air.

+38. Fifth Experiment.+--I took a silver solution prepared with acid of nitre, and precipitated it with alkali of tartar; I washed the precipitate thus obtained and dried it. I then placed this calx of silver in a small glass retort on the open fire for reduction, and fastened an empty bladder to the neck. The bladder was immediately expanded by the air which passed over. After the end of the distillation I found the calx of silver half melted together in the retort, with its metallic lustre; however, as I had effected the precipitation with alkali of tartar, and this is always united with a quantity of aerial acid which attaches itself to the calx of silver in the precipitation, so this acid was necessarily present also in the bladder. This acid was removed from it by milk of lime , and there remained behind one-half of pure fire-air.

+40. Seventh Experiment.+--It is likewise known that the red precipitate of mercury regains its flowing condition without the addition of an inflammable substance. Since mercury, however, really loses its phlogiston as well by means of vitriolic acid as of the acid of nitre, it must necessarily assume this again as soon as it recovers its metallic property.

I added a solution of alkali of tartar, drop by drop, to a solution of corrosive sublimate. I washed the brown-red precipitate obtained, and dried it; then I placed it, for reduction, upon the open fire in a small retort, which was provided with a bladder empty of air. As soon as the calx began to glow, the bladder became expanded, and quicksilver rose into the neck. The fire-air obtained had some aerial acid mixed with it.

Mercury converted into calx by the acid of nitre, or red 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 , and with fire .

+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 ? 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 , and which I have called vitiated air , 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.+-- 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.

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.

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 ? 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 , 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 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 . 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 to suit.

+49.+ I have mentioned 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....

+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 . 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 . 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. , 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 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.+-- I put 2 ounces of nitre into a small glass retort upon glowing coals, and attached a large bladder softened with water , 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 . 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. 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 with a cork, as also the tube B, and then filled the bottle with fire-air . 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 . 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.

I filled a bladder with the air which one obtains from iron filings and vitriolic acid , and respired it in the manner previously described . 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.

I kept a piece of sulphur in continuous ebullition over the fire in a retort, capable of holding 12 ounces of water, with an empty bladder attached in place of a receiver, the retort also placed so that the sulphur which rose into the neck could run back again. After all had become cold, I found the air neither increased nor diminished: it smelt slightly hepatic, and extinguished a burning candle. I shall prove further on that sulphur can unite with more phlogiston; and it seems to me to follow from this experiment that something inflammable from the air had deposited itself upon the sulphur, and that the air had thereby acquired the property of a vitiated air. It is, however, also remarkable that other bodies which attract the inflammable substance more strongly, as for example, the fuming acid of nitre, do not abstract it from the air. It is likewise strange that I was able to inhale the inflammable air into my lungs only 20 times; and I observe here as something peculiar that, if I mistake not, I became very warm a quarter of an hour afterwards. It is also to be observed that fire-air, vitiated by the lungs, extinguishes fire; why does not the aerial acid attract the phlogiston again? why not also the vitiated air? Mr. Priestley indeed has accomplished this, but it did not succeed with me however much I also wished it. He has converted aerial acid into wholesome air by means of a mixture of iron filings, sulphur, and some water. When I desired to repeat this experiment, the aerial acid was always absorbed by the iron filings. I likewise powdered finely some iron filings which had been fused together with excess of sulphur, moistened this with water, and preserved it in a bottle which was filled with aerial acid: but with the same result. After 2 two days the aerial acid was almost entirely absorbed. This philosopher also says that he has made vitiated air wholesome again by agitation with water. I must admit, however, that with me this likewise failed. I filled a flask one fourth part with vitiated air, and the remainder with fresh water; I closed the flask very tightly, and shook it up and down for almost a whole hour. Then when I collected this air in a bladder, and from this in a bottle, I found that the candle was extinguished afterwards as it was before. He mixed with water, by agitation, the inflammable air from metals; this also would not succeed with me, although I used only little inflammable air, and much water. He also observed that plants made vitiated air wholesome again. It follows from my experiments that they vitiate air. I kept plants, in the dark as well as exposed to sunlight, in a flask which was filled with vitiated air and carefully secured . I tested a little of this air every 2 days, and always found it vitiated.

+94.+ Water has the peculiar property of separating the proximate constituents of air; of uniting with fire-air; and of entering into no kind of union with vitiated air. I filled a large bottle with boiled water which had been cooled shortly before, and permitted the tenth part to run out. I then placed the bottle, inverted and open, in a vessel with water. I observed the quantity of air to diminish a little every day, and when this diminution ceased, I collected the remaining air first in a bladder , and from the bladder in a bottle , and brought a burning candle into the bottle; it had scarcely reached the mouth when it went out. I then took the same kind of water freed from air, filled a bottle with it, and permitted the tenth part of it to run into a bladder filled with vitiated air. I next placed the bottle, inverted, in a vessel with water, and observed the space which the air occupied in it. I found, 14 days afterwards, that the water had not absorbed the smallest quantity of it. I placed a large bottle, from which the bottom was knocked out, in a deep kettle with water, so that the water outside reached above the top of the bottle. I then tied a bladder, empty of air, over the top of the bottle, and made the water boil up once over the fire. The air which was in that portion of the water contained under the bottle rose into the bladder; and after I had tied up the bladder, and detached it front the bottle, I filled a phial with it, and put a small burning candle into it; it burned there more brightly than in ordinary air.

This fire-air, dissolved in water, must be as indispensable for aquatic animals as for those which live upon the earth. They must draw it into their bodies, and convert it either into aerial acid or into vitiated air. Into whichever kind it is, however, it must always become separated from the water again, for as aerial acid it does not remain with the water in the open air, and vitiated air cannot unite with water at all , the water is then in a condition again to absorb fire-air anew, and to convey it to the animals. My experiments made with respect to this matter agree with this entirely. I allowed a few leeches to remain in a bottle, which was half filled with water and well closed, until they died. I then examined the air standing over this water. It had no smell, nor had the water; it appeared to have increased a little and it extinguished fire. It seems that these creatures live only upon the phlogiston in fire-air, perhaps also upon the heat. I have preserved them alive in water, and that the same water, for two years; the bottle was only tied over with gauze. I have a convenient method to ascertain whether fire-air is present in water or not. I take, for example, an ounce of it, and add to it about 4 drops of a solution of vitriol of iron, and 2 drops of a solution of alkali of tartar which has been somewhat diluted with water. A dark green precipitate is immediately formed, which, however becomes yellow in a couple of minutes if the water contains fire-air; but if the water has been boiled, and has become cold without access of air, or if it is even a recently distilled water, the precipitate retains its green colour, and does not become yellow sooner than an hour afterwards, and not yellow at all if it is protected from access of air in full bottles. I have already shown that the green precipitate of iron owes its colour to phlogiston which still adheres to the earth, and it follows from this that fire-air, although not in the elastic condition, is able to attract phlogiston. The following experiment likewise shewed me that aquatic animals take fire-air from the water. I placed a leech in a bottle which was completely filled with water, and was protected from every kind of air. After two days it was almost dead. I then examined the water in the manner described above, and found that the earth of iron retained its green colour. The swelling up of peas in cold water is to be ascribed mainly to the fire-air present in the water. If a bottle is filled full of water and a few peas are placed in it, after 24 hours the water contains aerial acid it is true, but no fire-air. In water boiled and become cold, peas swell up only a little. I perceive in this the reason why the waters distilled from plants not only lose their smell, but why also a mucilaginous substance settles to the bottom, when the bottles are frequently opened, whereas the same waters, in perfectly full bottles, retain their smell and clearness unchanged. All plants communicate to water some mucilaginous material which is carried over along with it. Fire-air is the chief cause of this corruption; if this enters the water again, it attracts to itself the inflammable substance from the subtle oily and mucilaginous matter, and alters the whole of the water.

Transcriber's Note

All bold text has been surrounded by + signs. Italic text is denoted by underscores.

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