About alchemy, it must be noted that the "gold" that some alchemists sought was mystical enlightenment.
Misconceptions about Helmont's Willow Experiment. - In 1660, Jan-Baptista van Helmont planted a small willow tree in a bucket. He then watered it for the next five years, and he compared tree weights and soil weights both at the beginning and at the end. The tree gained much more than the soil lost, and Helmont interpreted it as the missing mass coming from water. He thought that his tree was mostly water with a little bit of earth mixed in, to use the traditional four elements: earth, water, air, and fire.
That's a rather laughable conclusion by present-day standards, but it took a LOT of effort to work out the element identifications of present-day chemistry. Along the way was a proposed element called phlogiston. It is released by burning and rusting and the like. But some substances lost mass when they burned, like wood, while others gained mass when they burned, like iron. So phlogiston was a confusing mess of an element, and that hypothesis was eventually abandoned as lacking in explanatory power.
Back then, the four terrestrial elements were
[TABLE="class: grid"]
[TR]
[TD][/TD]
[TD]Wet[/TD]
[TD]Dry[/TD]
[/TR]
[TR]
[TD]Hot[/TD]
[TD]Air[/TD]
[TD]Fire[/TD]
[/TR]
[TR]
[TD]Cold[/TD]
[TD]Water[/TD]
[TD]Earth[/TD]
[/TR]
[/TABLE]
I say "terrestrial" because a fifth element was recognized, a celestial one, quintessence ("fifth stuff") or aether.
These elements correspond to body fluids and temperaments in the following fashion:
[TABLE="class: grid"]
[TR]
[TD]Hot[/TD]
[TD]E+ Outward[/TD]
[TD]Dry[/TD]
[TD]N+ Negative[/TD]
[TD]Fire[/TD]
[TD]Yellow Bile[/TD]
[TD]Choleric[/TD]
[TD]Angry[/TD]
[/TR]
[TR]
[TD]Hot[/TD]
[TD]E+ Outward[/TD]
[TD]Wet[/TD]
[TD]N- Positive[/TD]
[TD]Air[/TD]
[TD]Blood[/TD]
[TD]Sanguine[/TD]
[TD]Joyful[/TD]
[/TR]
[TR]
[TD]Cold[/TD]
[TD]E- Inward[/TD]
[TD]Wet[/TD]
[TD]N- Positive[/TD]
[TD]Water[/TD]
[TD]Phlegm[/TD]
[TD]Phlegmatic[/TD]
[TD]Calm[/TD]
[/TR]
[TR]
[TD]Cold[/TD]
[TD]E- Inward[/TD]
[TD]Dry[/TD]
[TD]N+ Negative[/TD]
[TD]Earth[/TD]
[TD]Black Bile[/TD]
[TD]Melancholic[/TD]
[TD]Sad[/TD]
[/TR]
[/TABLE]
E = extroversion, N = neuroticism - two Big Five personality traits.
Melancholy is an old term for clinical depression, a sort of super sadness that is unprovoked and that does not go away.