Phlogiston theory

:Phlogiston is also the name of a substance in the fictional setting Spelljammer.

Theory

The theory holds that all flammable materials contain phlogiston (derived noun form of the Greek phlogistos, meaning flammable), a substance without color, odor, taste, or weight that is liberated in burning. Once burned, the "dephlogisticated" substance was held to be in its "true" form, the calx.

Related Topics:
Flammable - Greek - Color - Odor - Taste - Weight - Calx

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The theory is related to alchemical notions of the classical elements: fire, water, air, and earth. All substances were held to be a combination of these four elements.

Related Topics:
Alchemical - Classical elements - Fire - Water - Air - Earth

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"Phlogisticated" substances are those that contain phlogiston and are "dephlogisticated" when burned. Since any substance could be observed to burn for only a limited time with limited air (for instance in a sealed container), air was thought to have a specific capacity for phlogiston.

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Joseph Black's student Daniel Rutherford discovered Nitrogen in 1772 and the pair used the theory to explain his results. The residue of air left after burning, in fact a mixture of nitrogen and carbon dioxide, was sometimes referred to as "phlogisticated air", having taken up all of the phlogiston.

Related Topics:
Joseph Black - Daniel Rutherford - Nitrogen - 1772 - Carbon dioxide

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Conversely, when oxygen was first discovered it was thought to be "dephlogisticated air", capable of combining with more phlogiston and thus supporting combustion for longer than ordinary air.

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