Popular Science, lokakuu 1874
A remarkable and very beautiful shade of blue is noticeable upon many of the ornaments found in the tombs of Egypt. Analysis, come time since, proved the color to be formed by a combination of soda, sand, and lime, with certain proportions of copper. From these substances the ancient Egyptians obtained three different products: first, a peculiar kind of red, green, and blue glass; second, a brilliant enamel; and lastly, this blue color, which was used for painting. By synthetic experiments, Peligot has succeeded in reproducing this peculiar shade of blue, by heating together seventy-three parts of silica, with sixteen of oxide of copper, eight of lime, and three of soda. The temperature should not exceed 800° Fahr., as, in such case, a valueless black product is the result.