Chemical wedding or marriage, sometimes called coniunctio, in alchemy is the joining of the male elements (fire and air that are represented by sulphur) with the female elements (water and earth that are represented by argent vive or quicksilver) in philosophical mercury.
This supposedly symbolizes the gold, King Sol, and silver, Queen Luna, respectively. This final fusion of opposites produces the philosopher’s stone. A.G.H
Drury, Nevil. The Watkins Dictionary of Magic. London. Watkins Publishing. 2005. p. 56