Scientific American 42, 7.7.1849
The following new paints are described in the Philadephia Ledger, as discoveries made by H. M. A. Mahn, last year.
Sulphate of copper, 2 parts; alum 1 part; brown sugar 8 parts, and yellow soap 8 parts; Make a hot solution of the blue vitriol in a proper quantity of water, then add the alum, then put in the sugar, which will almost instantly convert the blue into green; the solution of soap must now be added, which must have been previously made; both solutions being boiling hot at the moment of their junction. The article supercedes the old verdigris, both in durability and color, and will stand all kinds of weather.
This pigment was discovered May 29, 1848. Its preparation is as follows: - 1 pound sulphate of copper, 2 ounces alum, and 1 pound good light yellow soap; make a solution of the vitriol in a sufficient quantity of hot water, then add the alum, then pour int the soap, having also been prepared in boiling water to the consistency of cream - a beautiful green immediately floats on the surface.
Several other kinds can be made, by varying the proportions or adopting the different methods. This paint can be used immediately on being made, by being dissolved in a little warm oil or spirits of turpentine and mixed with some white lead or chrome yellow, &c. so as to make it corporeal and heavy.
For Japan were it is excellent, without any admixture; for making marine paint it is very good; for coloring wax, it is better than most other greens, and in point of cheapness and facility of its production it excels all other pigments.