The Pneumatics of Hero of Alexandria

...vanishes. Wherefore it is mixed, and it itself becomes earth. But if anyone should say that it is subdued, and not absorbed by the earth, but evaporates and is dried out by the heat of the sun or some other source, he will be found to speak falsely. For if the same water is poured into some vessel—whether glass or bronze, or consisting of another dense material—and exposed to the sun for a long time, it is not diminished, except in a very small part of itself. Therefore, water is also changed into an earthy substance; for mud original: "limus" and mire original: "caenum" are transformations of water into an earthy substance.

A thinner substance is also changed into a thicker one; just as we see that even the flame from extinguished lamps, when the oil fails, is carried upward a little and, as if propelled, withdraws into its "own place." In ancient physics, the "natural place" of fire was the highest sphere, located above the air. Objects were believed to seek their natural home based on their elemental composition. Now, I speak of the highest place, which is above the air; but having been overcome by the vast amount of intervening air, the flame is no longer carried to its intended place, but being mixed and entwined with the bodies of the air, it is turned into air.

Something similar must also be understood regarding air. For when it exists in some vessel that is not large and is closed off...

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