THE BLACK MARBLE.
It was formerly an unknown thing to produce a black marble over which a net of light-colored veins was stretched. My investigations have resulted in my becoming able to produce this brilliant and effective marble.
The colors used are scarlet-red, bluish-green and gall water, the latter representing the white, this network of veins comes out excellently from the dark ground-tone. The scarlet-red color is first taken and must spread out in a like way, as the black in the other two marbles. Then follows bluish-green and gall-water and finally the body color is added. The latter makes a special preparation necessary. Take 3/5 of an ounce of ivory-black add 1/6 of an ounce of a thick solution of gum, grind the whole mixture with a mixture of shellac-ammonia which has been diluted with a little water. If the color is ground perfectly fine it is diluted with the solution of shellac-ammonia and is ready for use. Should it not be powerful enough to force the colors into veins, a few more drops of gall must be added. This body color is likewise thrown on by the aid of the large bristle brush as all other body colors.
As beautiful as this kind of marbling may be, there is a disadvantage in its use as the body color must always be newly prepared, because on the second day after standing it curdles, and cannot be used any more.