Arsenic Alchemy Symbol

Many seemingly unrelated symbols have been used to denote the element arsenic. Several glyph shapes included a cross and two circles or an S-shape. A stylized swan was also used to depict the element.

Arsenic was a well-known poison at the time, so the swan symbol might not make much sense - until you remember that the element is a metalloid. Like other elements of the group, arsenic can change from one appearance to another; these allotropes have different properties from each other. Swans turn into swans; arsenic is also transformed.