Marking Ink.
Put two pennyworths’ lunar caustic (nitrate of silver) into half a tablespoonful of gin, and in a day or two the ink is fit for use. The linen to be marked must first be wet with a strong solution of common soda, and be thoroughly dried before the ink is used upon it. The color will be faint at first, but by exposure to the sun or the fire it will become quite black and very durable.
Blue Marking Ink for White Goods.
| Crystallized nitrate of silver, dram | 1 | |
| Water of ammonia, drams | 3 | |
| Crystallized carbonate of soda, dram | 1 | |
| Powdered gum arabic, drams | 1½ | |
| Sulphate of copper, grains | 30 | |
| Distilled water, drams | 4 |
Dissolve the silver salt in the ammonia; dissolve the carbonate of soda, gum arabic, and sulphate of copper in the distilled water, and mix the two solutions together.
Blue-Black Writing Paper.
Take of Aleppo galls, bruised, 9 ozs.; bruised cloves, 2 drachms; cold water, 80 ozs.; sulphate of iron, 3 ozs.; sulphuric acid, 70 minims; indigo-paste, 4 drachms. Place the galls and the cloves in a gallon bottle, pour upon them the water, and let them macerate, with frequent agitation, for a fortnight. Press, and filter through paper into another gallon bottle. Next, put in the sulphate of iron, dissolve it, add the acid, and shake the whole briskly. Lastly, add the indigo-paste, mix well, and filter again through paper. Keep the ink in well-corked bottles.
Coloring Metals.
Metals may be rapidly colored by covering their surfaces with a thin layer of sulphuric acid. According to the thickness of the layer and the durability of its action, there may be obtained tints of gold, copper, carmine, chestnut-brown, clear and aniline blue and reddish-white. These tints are all brilliant, and if care be taken to scour the metallic objects before treating them with the acid, the color will suffer nothing from the polishing.