The symbol for sulfur stood for more than just the chemical element. Together with mercury and salt, the trio made up the Three Primes, or Tria Prima, of alchemy. The three primes could be thought of as points of a triangle. In it, sulfur represented evaporation and dissolution; it was the middle ground between the high and low or the fluid that connected them.

The symbol for mercury stood for the chemical element, which was also known as quicksilver or hydrargyrum. It was also used to represent the swiftly moving planet Mercury. As one of the three primes, mercury reflected both the omnipresent life force and a state that could transcend death or Earth.

Modern scientists recognize salt as a chemical compound, not an element, but early alchemists did not know how to separate the substance into its components to come to this conclusion. Simply, salt was worth its own symbol because it is essential for life. In the Tria Prima, salt stands for condensation, crystallization, and the underlying essence of a body.

There were several possible element symbols for the metal copper. The alchemists associated copper with the planet Venus, so sometimes, the symbol for "woman" was used to indicate the element.

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