Arsenic is a naturally occurring crystalline metalloid and is possibly one of the most well known and common poisons used as a murder weapon in the late 19th century. However, its known use in such a capacity goes back to the mid 1700's. Arsenic poisoning can kill in a few hours to a few days. Symptoms are vomiting and diarrhea, which made it difficult to distinguish from dysentery or cholera 120 years ago.