The free sulfur or polluting sulfides may react with lead white. Many people strongly warn against mixing cadmiums with lead white. I m not the only one who thinks its day as an artist s pigment is long past. True, but there are plenty who say the same thing about Flake White, and the cadmiums. Of course, people need to know what they're doing.
Mercuric sulfide is insoluble in water.
This makes it far less dangerous than soluble mercury compounds. Vermilion contains insoluble Mercury. That's a huge difference. Emerald green is certainly not suited for mainstream use today. However, it can be sufficiently lightfast and reliable if made properly and used correctly.