You probably haven’t heard before that Antoine Laurent Lavoisier, also known as the father of modern chemistry, set the precious diamonds on fire in 1772. But those who know say that this interesting event is one of the unforgettable memories in the life of the famous scientist.
When Lavoisier was born, chemistry was still not at the point where it could be called a science. Beliefs supported the theory of phlogiston, the idea that all combustible materials contain a fire-like element (called phlogiston) that is released as it burns and is taken up by the surrounding air. The theory was that the flame would go out when the air was so saturated with phlogiston that it could no longer absorb it.
Lavoisier had different and less ancient ideas, with what he discovered during experiments in which he burned sulfur and phosphorus. He knew that both substances gained weight after burning, and he believed that they combined with air to gain weight.
Lavoisier had also heard of an experiment by the English natural philosopher Joseph Priestley. This experiment involved heating red mercury oxide. The colorless gas resulting from the experiment was called “phlogistic-free air” by Priestley, but Lavoisier would later prove it was oxygen.
Diamonds are involved
As for diamonds, at that time people believed that these gemstones were a special substance that had nothing to do with materials such as coal and graphite. Curious to break down the ingredients into their most basic forms, Lavoisier took a diamond, placed it in a sealed jar filled with oxygen, and tried to burn it, using a giant magnifying glass to focus the sun’s rays.
Although diamonds are renowned for their durability, they can burn when there is an adequate supply of oxygen. This contradicted the phlogiston theory, as if the burning element was in the diamond and air (oxygen) was not part of the process, it would certainly burn in any environment. Predictably, the diamond burned during the experiment. Lavoisier’s suspicion that it was made of carbon was correct.
For someone who couldn’t see the practical side of burning one of the world’s most precious stones, even more important was the weight balance of his entire experiment. Although the diamond burned, the weight of the jar and its contents remained exactly the same.
As with other combustion experiments, he had obtained evidence that matter was neither created nor destroyed in chemical reactions, but instead preserved.
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