III. Dr. W. Reissig’s formula:
| Boiled linseed oil varnish | 16 | parts. |
| Finest lamp black | 6 | ” |
| Ferric chloride (sesquichloride of iron) | 2 to 5 | ” |
Dilute a little for use with varnish. After this ink has been removed, no matter how completely it can be detected by dipping the paper into a solution of ammonium sulphide.
IV.
| Aniline black in crystals | 1 | part. |
| Alcohol | 30 | ” |
| Glycerine | 30 | ” |
Dissolve in the alcohol, and add the glycerine afterwards.
Show Card Ink.—
| Pure asphaltum | 16 | parts. |
| Venice turpentine | 18 | ” |
| Lamp-black | 4 | ” |
| Oil of turpentine | 64 | ” |
Dissolve the asphaltum in the turpentine, and thoroughly mix.
Stencil Ink.—Shellac, 2 ounces; borax, 2 ounces; water, 25 ounces. Dissolve by heat if necessary, first the borax alone, and then adding the shellac. To the clear solution add gum arabic, 2 ounces. Color with lamp-black, with Venetian red, or with ultramarine, to suit the taste. Another formula gives shellac, 4 parts, borax, 1 part, and omits the gum arabic.