The Greek Elements (Aristotle)
Aristotle adopted the concept of four elements and introduced the idea that the elements can be differentiated on the basis of properties such as hot versus cold and wet versus dry, as shown below.
The four Greek elements differed in two properties: hot versus cold and dry versus wet.
Fire: hot and dry
Air: hot and wet
Water: cold and wet
Earth: cold and dry
One substance could therefore be changed into another by changing the relative proportions of the four elements. Heating clay in an oven, for example, could be thought of as driving off water and adding fire, thereby transforming the clay into a pot. Alternatively, substances could be changed into one another by changing one of the properties that made the elements different from each other. Water (cold and wet) falls from the sky as rain, for example, when the air (hot and wet) cools down. A piece of wood, on the other hand, which is obviously rich in earth (cold and dry), bursts into flame (hot and dry) when heated.
|History of Chemistry|