[wiki](https://en.wikipedia.org/wiki/Agathodaemon_(alchemist)):

> works of his believed to be from the 3rd century

> primarily remembered for his various descriptions of elements and minerals, most particularly his descriptions of a method of producing silver,[1] and of a substance he had created, which he called a 'fiery poison', and which, judging by his account, was arsenic trioxide, a highly toxic amphoteric oxide.

> Agathodaemon's discoveries exist as part of the foundations for later use of poison, as arsenic and related substances were used regularly in later centuries as means of poisoning and murder.