To dream of quicksilver represents rapid changes, or unpredictability. Your thoughts, feelings, choices, or life situation may be subjected to fast or unpredictable changes. A constant sense of being luckier.
Alternatively, mercury may reflect feelings of being tainted that you wish to perfectly avoid. Trying to be extra careful to avoid a mistake with permanent consequences.
To dream of ingesting mercury may reflect lingering guilt or regret that feels very difficult to forget. Feelings of never being able to be perfect or innocent again if you accept or go through with a choice. Negative feelings that are difficult to shed. Feeling that life will never be the same again due to some corrupting factor.