From the outset wallpaper was often colored with pigments that used large doses of arsenic, lead, and antimony, but after 1775 it was frequently soaked in an especially insidious compound called copper arsenite, which was invented by the great but wonderfully hapless Swedish chemist Karl Scheele.* The color was so popular that it became known as Scheele's green. Later, with the addition of copper acetate, it was refined into an even richer pigment known as emerald green. This was used to color all kinds of things--playing cards, candles, clothing, curtain fabrics, and even some foods. But it was especially popular in wallpaper.