Answer:
Arsenic
Step-by-step explanation:
Spanish scientist Mathieu Orfila, known as the "father of toxicology" for his work in the area, published one of the first books about poisons and medications. In his book, Orfila not only recapitulated what was known about various poisons and toxins at the time, but also attempted to label the poisons and toxins by their characteristics. One of them is arsenic, which is a heavy metal that is toxic to humans.