I want to know the answer to the following question:
What is made by placing a plate of blade of copper, brass, or bronze into vat of fermenting wine for several weeks, then scraping off and drying the green powder?
All the background I'm provided with is that "It produced a blue-green which no other pigment could imitate, but it had drawbacks; it was unstable, it could not resist dampness, it did not mix well with other colors, it could ruin other colors with which it came into contact., and it was toxic.". Is that enough to answer the question?