sunlight, and when well made are excellent pigments

Gas-black is the soot from the partial combustion of a hydrocarbon gas; the pigment must be an impact black, free from grit and dirt. It is not suitable for mixing with white lead or zinc for making tints. The particles of gas-black are said to be in form of little stars, while those of lamp-black have that of filaments.

Bone-black.—A black made by burning bones in retorts or furnaces without air, just as charcoal is made from wood. The mineral matter of the bones is, of course, all retained in the finished product.

Oxides of Iron

Oxide of iron pigments are obtained from natural and artificial sources; they vary largely  in  their  characteristics, and in their