1780, Lavoisier et la respiration

Summary

The script delves into key historical experiments that revealed the vital role of air in respiration. Starting with Boyle's invention of the vacuum pump in the 17th century, the narrative moves to Lavoisier's discovery in 1777. Lavoisier observed that respiration is akin to combustion but without the visible flame, suggesting that both processes require atmospheric air. Alongside mathematician Pierre-Simon Laplace, Lavoisier proved that respiration, like combustion, consumes oxygen. Their groundbreaking work paved the way for understanding the biochemical process, though Lavoisier's research was cut short by his execution in 1794, marking the end of an era in chemistry.

Takeaways

• 😀 Robert Boyle invented the vacuum pump in 1660, greatly influencing both science and imagination.
• 😀 The necessity of respiration for life has been known for a long time, but what is truly essential in the air remained a mystery.
• 😀 In 1777, Antoine Laurent Lavoisier conducted an experiment with a sparrow under a glass bell, leading to a key discovery about the air.
• 😀 After 55 minutes of being in a sealed, oxygen-deprived environment, the sparrow died, showing that the air had changed significantly.
• 😀 Lavoisier observed that the air breathed by the sparrow was different from atmospheric air and had properties like extinguishing flames.
• 😀 He noticed similarities between the gases produced during respiration and those released during combustion.
• 😀 Both combustion and respiration require atmospheric air, but combustion releases heat while respiration does not.
• 😀 Lavoisier, with mathematician Pierre-Simon Laplace, discovered that respiration is a slow form of combustion.
• 😀 Using an experimental calorimeter, they showed that respiration and combustion produced similar heat and oxygen consumption levels.
• 😀 Lavoisier concluded that respiration occurs in the muscles, not the lungs, although he identified the crucial principle of respiration.
• 😀 Lavoisier's work on respiration and combustion was interrupted by his execution in 1794, but it remains foundational to modern chemistry.

Q & A

What was the key question Lavoisier sought to answer through his experiments on respiration?

Lavoisier sought to understand what is truly essential in the air we breathe and the role of oxygen in respiration, which was still a mystery at the time.

What was the main result of Lavoisier's experiment with a sparrow under a glass bell?

Lavoisier discovered that when a sparrow was placed under a bell jar with common air, it died after 55 minutes, suggesting that air changed after being breathed by an animal and became harmful, which hinted at the importance of oxygen.

How did Lavoisier relate respiration to combustion?

Lavoisier found that respiration is essentially a slow form of combustion, as both processes require oxygen and produce heat. However, respiration does not emit visible light, unlike combustion.

What did Lavoisier and Pierre-Simon Laplace discover by using a calorimeter on a guinea pig?

They found that the heat produced by the guinea pig's respiration and the oxygen consumed were in the same proportions as those observed in combustion, demonstrating that respiration is a form of combustion.

What was the difference between the combustion of charcoal and the respiration of an animal, according to Lavoisier?

The key difference is that combustion produces visible light and occurs outside the body, while respiration is a slow combustion process that happens within the body and does not produce visible light.

Why did Lavoisier believe the combustion took place in the lungs, and what was later discovered?

Lavoisier initially thought that combustion occurred in the lungs due to the exchange of gases there, but it was later discovered that the actual combustion-like process happens in the muscles.

What was the role of oxygen in both respiration and combustion as demonstrated by Lavoisier's experiments?

Oxygen was shown to be essential for both respiration and combustion, as both processes consume oxygen and release heat, with respiration being a slower version of combustion.

How did Lavoisier's work contribute to the development of modern chemistry?

Lavoisier's work, particularly his experiments on respiration and combustion, laid the foundation for modern chemistry by proving the role of oxygen in both biological and chemical processes.

What instrument did Lavoisier and Seguin develop to measure oxygen consumption?

Lavoisier and Seguin developed a 'respirometer,' which allowed them to measure oxygen consumption based on physical activity, further confirming the relationship between oxygen use and metabolism.

What happened to Lavoisier's work and career in 1794?

Lavoisier's work and career were abruptly interrupted when he was executed during the Reign of Terror in 1794, despite his major contributions to science.