One goal of alchemy has been to transmute base metals like copper into silver or gold. Alchemists judged the success of their operation primarily on the color of their product. Accordingly, the operation was called tingeing. After an initial blackening, the base metal could be whitened with an arsenic compound, yellowed to gold with a sulfur compound, or given a silvery color with mercury.
Mercury, recovered from graves as early as the fifteenth century BCE, was well known to the alchemists of Miriam bat Isaac’s time as was its preparation by the roasting of cinnabar, its bright red ore.
Although mercury was used medicinally throughout much of history, it is extremely toxic. The roasting of cinnabar releases its vapors. This acute exposure results in
such breathing difficulties as coughing and then bronchitis, pneumonia, and pulmonary edema. Chronic inhalation of the vapors, that is, repeated exposure over time, leads to central nervous system disorders such as tremors, insomnia, depression, and explosive irritability.
In The Deadliest Lie, Miriam ultimately identifies the thief of the alchemical recipe entrusted to her by the telltale symptoms of mercury poisoning.