New Chrome Reds.

Manufacturer and builder 10, 1869

Chrome Mercury. - Chromates of potash give, both with the mercurial protoxide and deutoxide salts, a beautiful red precipitate, which may be used as well for oil as water-colors. Experience, however, has shown that sulphuric vapors act on it even snore than on lead colors, and that in oil it becomes darker in the course of time; we therefore doubt if it will ever supersede vermilion, which is more constant and of no higher price. Different shades may be made from solutions of bichloride of mercury, nitrate of mercury, or any other suitable salt; or calomel, which is an insoluble sub-chloride, may be boiled with a solution of chromate of potash.

A much more important compound of this class is Chrome Tin, or Pink Color  - Thus far this color has not been much used as a paint, but has chiefly been applied in pottery as a porcelain paint and printing color. It has, however, been found that it forms a most excellent color for painters, perfectly equal to a clear madder lake, over which it has the great advantage of resisting perfectly all exterior influences, which deteriorate, in the first place, vegetable pinks, as madder, carmine lake, etc.; consequently we are satisfied that if it were better known it would find extensive application.

To make this pink color, it is best to oxidize granulated tin by means of nitric acid. For the oxide obtained from thirty ounces tin, take three ounces chromate of potash, dissolve in about thirty ounces water, mix with it sixty ounces chalk and thirty ounces ground quartz sand, make it to a paste, and then add slowly the oxide of tin and mix it as perfectly as possible. The yellow mass is now dried in a warm place, and is then pulverized and once more rubbed up, in order to mix it still better. Then it is firmly packed in a Hessian crucible, and heated for a few hours in the bright flame of a wind furnace, or exposed in a pottery furnace. After cooling, the substance in the crucible is found melted together and changed into a dark pink mass of unequal color. It is then ground very finely in a paint-mill, and when once more heated the color becomes better, and still more beautiful if a soda salt be added. It is then ground with water, washed, filtered, and dried. Nearly one hundred and twenty ounces of color are thus obtained, which by appropriate mixing and heating possesses the beautiful rose-pink tint of light-colored madder lake, and, as above mentioned, is one of the most unchangeable colors existing, being, perhaps, the only mineral and perfectly permanent paint of that peculiar shade of color.

It is clear from the mode of manufacture described that the substance is a silicate of lime and potash, a true glass, colored with chromate of tin; and there-fore similar to the cobalt blue, which is also a finely-ground glass, colored with the oxide of cobalt.