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Authors: Gabrielle Walker
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closed glass vessel with fifty cubic inches of common air. Then he heated it almost to its boiling point and kept it that way for twelve days. At the beginning, nothing much happened. But gradually red specks began to appear on the mercury's silver surface, and they grew larger each day. By the end of the twelve days, the reaction seemed to be at an end. Lavoisier had lost nine cubic inches of air and gained forty-five grains of red
mercurius calcinatus.
The air left behind in the vessel would not permit a candle to burn, but unlike fixed air it did not turn lime-water cloudy. This was some other form of air that apparently existed only to dilute the vibrant, active part.
With the utmost care, Lavoisier collected the forty-five red grains and put them in a small glass jar whose long, thin neck twisted around itself
several times and then poked up into a bell jar full of water. Now all he had to do was heat the grains of
mercurius calcinatus.
As he did so, out and up bubbled the very air they had trapped within them. Exactly nine cubic inches made their way into the bell jar above. As a final proof, Lavoisier took this air and recombined it with the stuff that had been left behind from the first experiment, the stuff that would not support burning but would neither turn lime-water cloudy. Immediately this mixture became indistinguishable from common air. Candles burned normally in it; animals breathed happily for exactly as long as you would expect.
Lavoisier had found the magic ingredient, the active part of the air. He had extracted it, trapped it inside mercury, released it, and recombined it with the passive part to regenerate common air. By applying his painstaking system of accounting to science, he had looked into the heart of a flame. He now knew what fed every fire on Earth.
But what to call it? Lavoisier had no patience with Priestley's name for this new gas, "dephlogisticated air." His experiments had clearly proved that burning had nothing to do with phlogiston and everything to do with the presence or absence of this one crucial active ingredient. Instead, since it seemed to be trapped in many different kinds of acid, he named it "oxygene," which means "acid-born."
Lavoisier was intrigued with his new gas and began to work on it in earnest. In particular he wanted to know more about the relationship between burning and breathing, and the role that oxy-gene might play in each. Like Priestley, Lavoisier had noticed the similarity between these two processes. Place a burning candle in a closed jar of common air and eventually the flame will sputter and die. Place a living mouse in such a jar and after a while the animal will no longer be able to breathe. To Priestley, both candle and mouse were giving out phlogiston. To Lavoisier, both were using up oxy-gene. And now, he wondered how far the similarity between the two processes went. How could the same substance that fed a flame also feed life itself?
Until now, nobody had made any truly systematic investigations into the nature of breathing. Obviously, it was necessary for life. And just as obviously, food somehow sustained life. But there was no sense that food in a
person was like fuel in a machine. Aristotle had believed that the purpose of breathing was to cool the blood, and this was still a popular notion even in Lavoisier's time. Other philosophers thought that breathing in a confined space became increasingly difficult because it reduced the elasticity of the air, which prevented it from pushing back enough to inflate the lungs properly. As to what relationship this had to eating, nobody really knew.
So, Lavoisier began his experiments. Unusually for him, he performed them with a collaborator, a young mathematical genius named Pierre-Simon Laplace. Among his other achievements, Laplace would later produce the complex equations that govern the behavior of the solar system, and it is sometimes said that his efforts in this regard were halted because his
mercurius calcinatus.
The air left behind in the vessel would not permit a candle to burn, but unlike fixed air it did not turn lime-water cloudy. This was some other form of air that apparently existed only to dilute the vibrant, active part.
With the utmost care, Lavoisier collected the forty-five red grains and put them in a small glass jar whose long, thin neck twisted around itself
several times and then poked up into a bell jar full of water. Now all he had to do was heat the grains of
mercurius calcinatus.
As he did so, out and up bubbled the very air they had trapped within them. Exactly nine cubic inches made their way into the bell jar above. As a final proof, Lavoisier took this air and recombined it with the stuff that had been left behind from the first experiment, the stuff that would not support burning but would neither turn lime-water cloudy. Immediately this mixture became indistinguishable from common air. Candles burned normally in it; animals breathed happily for exactly as long as you would expect.
Lavoisier had found the magic ingredient, the active part of the air. He had extracted it, trapped it inside mercury, released it, and recombined it with the passive part to regenerate common air. By applying his painstaking system of accounting to science, he had looked into the heart of a flame. He now knew what fed every fire on Earth.
But what to call it? Lavoisier had no patience with Priestley's name for this new gas, "dephlogisticated air." His experiments had clearly proved that burning had nothing to do with phlogiston and everything to do with the presence or absence of this one crucial active ingredient. Instead, since it seemed to be trapped in many different kinds of acid, he named it "oxygene," which means "acid-born."
Lavoisier was intrigued with his new gas and began to work on it in earnest. In particular he wanted to know more about the relationship between burning and breathing, and the role that oxy-gene might play in each. Like Priestley, Lavoisier had noticed the similarity between these two processes. Place a burning candle in a closed jar of common air and eventually the flame will sputter and die. Place a living mouse in such a jar and after a while the animal will no longer be able to breathe. To Priestley, both candle and mouse were giving out phlogiston. To Lavoisier, both were using up oxy-gene. And now, he wondered how far the similarity between the two processes went. How could the same substance that fed a flame also feed life itself?
Until now, nobody had made any truly systematic investigations into the nature of breathing. Obviously, it was necessary for life. And just as obviously, food somehow sustained life. But there was no sense that food in a
person was like fuel in a machine. Aristotle had believed that the purpose of breathing was to cool the blood, and this was still a popular notion even in Lavoisier's time. Other philosophers thought that breathing in a confined space became increasingly difficult because it reduced the elasticity of the air, which prevented it from pushing back enough to inflate the lungs properly. As to what relationship this had to eating, nobody really knew.
So, Lavoisier began his experiments. Unusually for him, he performed them with a collaborator, a young mathematical genius named Pierre-Simon Laplace. Among his other achievements, Laplace would later produce the complex equations that govern the behavior of the solar system, and it is sometimes said that his efforts in this regard were halted because his
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