These are also frequently called waterproof, incorrodible, or indestructible inks. They are employed for writing labels on bottles containing strong acids and alkaline solutions. They may be employed with stamps, types or stencil plates, by which greater neatness will be secured than can be obtained with either a brush or pen.
The following is a superior preparation for laundry use:
| Aniline oil | 85 parts |
| Potassium chlorate | 5 parts |
| Distilled water | 44 parts |
| Hydrochloric acid, pure (specific gravity, 1.124) | 68 parts |
| Copper chloride, pure | 6 parts |
Mix the aniline oil, potassium chlorate, and 26 parts of the water and heat in a capacious vessel, on the water bath, at a temperature of from 175° to 195° F., until the chlorate is entirely dissolved, then add one-half of the hydrochloric and continue the heat until the mixture begins to take on a darker color. Dissolve the copper chloride in the residue of the water, add the remaining hydrochloric acid to the solution, and add the whole to the liquid on the water bath, and heat the mixture until it acquires a fine red-violet color. Pour into a flask with a well-fitting ground-glass stopper, close tightly and set aside for several days, or until it ceases to throw down a precipitate. When this is the case, pour off the clear liquid into smaller (one drachm or a drachm and a half) containers.
This ink must be used with a quill pen, and is especially good for linen or cotton fabrics, but does not answer so well for silk or woolen goods. When first used, it appears as a pale red, but on washing with soap or alkalies, or on exposure to {406} the air, becomes a deep, dead black. The following is a modification of the foregoing:
Blue Indelible Ink.
Red Indelible Inks.
| 1.— | Sodium carbonate | 3 drachms |
|---|---|---|
| Gum arabic | 3 drachms | |
| Water | 12 drachms | |
| 2.— | Platinic chloride | 1 drachm |
| Distilled water | 2 ounces | |
| 3.— | Stannous chloride | 1 drachm |
| Distilled water | 4 drachms |
Moisten the place to be written upon with No. 1 and rub a warm iron over it until dry; then write with No. 2, and, when dry, moisten with No. 3. An intense and beautiful purple-red color is produced in this way. A very rich purple color—the purple of Cassius—may be produced by substituting a solution of gold chloride for the platinic chloride in the above formula.