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 the air, becomes a deep, dead black. The following is a modification of the foregoing:

Blue Indelible Ink

This ink has the reputation of resisting not only water and oil, but alcohol, oxalic acid, alkalies, the chlorides, etc. It is prepared as follows: Dissolve 4 parts of gum lac in 36 parts of boiling water carrying 2 parts of borax. Filter and set aside. Now dissolve 2 parts of gum arabic in 4 parts of water and add the solution to the filtrate. Finally, after the solution is quite cold, add 2 parts of powdered indigo and dissolve by agitation. * Let stand for several hours, then decant, and put in small bottles.

Red Indelible Inks

By proceeding according to the following formula, an intense purple-red color may be produced on fabrics, which is indelible in the customary sense of the word:

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 porduced 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.

Crimson Indelible Ink

The following formula makes an indelible crimson ink:

Silver nitrate....... 50 parts

Sodium carbonate, crystal........... 75 parts

Tartaric acid....... 16 parts

Carmine........... 1 part

Ammonia water, strongest......... 288 parts

Sugar, white, crystallized ............ 36 parts

Gum arabic, powdered ........... 60 parts

Distilled water, quantity sufficient to make.......... 400 parts

Dissolve the silver nitrate and the sodium carbonate separately, each in a portion of the distilled water, mix the solutions, collect the precipitate on a filter, wash, and put the washed precipitate, still moist, into a mortar. To this add the tartaric acid, and rub together until effervescence ceases. Now, dissolve the carmine in the ammonia water (which latter should be of specific gravity .882, or contain 34 per cent of ammonia), filter, and add the filtrate to the silver tartrate magma in the mortar. Add the sugar and gum arabic, rub up together, and add gradually, with constant agitation, sufficient distilled water to make 400 parts.

Gold Indelible Ink

Make two solutions as follows:

1

Chloride of gold and

sodium.........     1 part

Water............   10 parts

Gum.............     2 parts

2

Oxalic acid....... 1 part

Water............ 5 parts

Gum............. 2 parts

The cloth or stuff to be written on should be moistened with liquid No. 2. Let dry, and then write upon the prepared place with liquid No. 1, using preferably a quill pen. Pass a hot iron over the mark, pressing heavily.