For this design the cover must be finely sprinkled over three separate times, leaving the colour to search and dry between each. The green must be brought to the shade required by mixing with water. To form a more elegant vein, sprinkle first with weak black, and afterwards with green, and when dry with fine red.
PORPHYRY.
This marble, imitating the eye of the partridge, is executed by throwing on black in eight times its volume of water, in small drops, but so close as to just run into each other. When the black begins to flow, sprinkle over brown mixed equally with water. Let it dry, wash the whole with a sponge, and before quite dry again give it two or three coats of fine red. After being dry and well rubbed, sprinkle equally over the surface large drops of aqua regia.
ANOTHER.
Colour the cover with red, yellow, blue, or green, and, when dry, with black diluted as above; let this also dry, and then sprinkle over large or small drops of aqua regia. The eye of the partridge is properly formed with blue sprinkled upon the weakened black, and, when dry, with the killed spirit or aqua regia.
ROCK.
Throw on large drops of black prepared as for the porphyry, and, when half dry, weakened potash in the same manner. When dry again, sprinkle on equally small spots of scarlet, and lastly aqua regia.
GRANITE.
Mix black in about fifty times its quantity of water, and sprinkle equally over very fine, repeating it as it dries five or six times. Then, in like manner, sprinkle over with brown, and, after rubbing well, glaire lightly. Finally, sprinkle finely over with aqua regia.