King Sol, «King Sun,» is the embodiment in alchemy of the male qualities of «hot and dry» associated with the sun, sulphur, and gold.
The king unites with the receptive qualities «cold and moist» of the female principle represented by the queen, Queen Luna, in a chemical wedding in the process of producing the philosopher’s stone.
During this process the king experiences death and resurrection, suffering putrefaction and becoming dissolved within the original matter of creation, the prima materia.
The term «king» was also applied to the stone itself after its various stages from imperfection to perfection.
When finally cleansed and purified King Sol becomes the «red stone» or the «mighty king» who according to the alchemist Edward Kelly could change base metals into genuine gold. A.G.H
Source:
Drury, Nevil. The Watkins Dictionary of Magic. London. Watkins Publishing. 2005. p. 159