Paraquat

CAS RN: 4685-14-7

Color / Form

Yellow solid
Off-white powder
...a liquid in various strengths... The form marketed in the U.S. has a blue dye to keep it from being confused with beverages, a sharp odor to serve as a warning, and an agent to cause vomiting if someone drinks it.
Yellow-white hygroscopic powder
Find more information on this substance at: PubChem, PubMed