1988. To Dye Ivory Purple

1988.    To Dye Ivory Purple. Steep in a weak neutral solution of terchloride of gold, and then expose it to the light. Or, soak the ivory in a solution of sal ammoniac into 4 times its weight of nitrous acid.

1989. To Dye Ivory Green

1989.    To Dye Ivory Green. Dissolve verdigris in vinegar, and steep the pieces therein for a short time, observing to use a glass or stoneware vessel; or in a solution of verdigris, 2 parts, and sal ammoniac, 1 part, in soft water; or, dye the ivory blue by the third receipt for that purpose, and then insert in a solution of picric acid, as prescribed for the dark lemon color. (See No. 1991 (To Dye Ivory Dark Lemon).)

1990. To Dye Ivory Yellow

1990.    To Dye Ivory Yellow. Steep the ivory in a bath of neutral chromate of potash, and afterwards in a boiling solution of acetate of lead.

Or: Steep the pieces for 24 hours in a solution of sugar of lead, then take them out, and when dry, immerse them in a solution of chromate of potassa.

Or: Dissolve as much of the best orpiment in water of ammonia or hartshorn as it will take up, then steep the pieces therein for some hours; lastly, take them out and dry them, when they will turn yellow.

1991. To Dye Ivory Dark Lemon

1991.    To Dye Ivory Dark Lemon. Dissolve 1/4 ounce picric acid in 1/2 ounce boiling water. Dilute 1/8 ounce strong sulphuric acid with 1/4 ounce hot water, by pouring the acid gradually into the water. Insert the ivory in the acidulated water, turn it around repeatedly, in order to admit the acid to all parts, remove the ivory from the fluid and dry it. Then insert the dried ivory in the boiling solution of picric acid, turn it also around, and leave it in the solution until all parts appear of a uniform yellow color. Then remove it from the solution of picric acid, dry, and polish the ivory with soap water and finely levigated chalk. After the polishing the ivory possesses a permanent dark lemon-yellow color.

1992. To Dye Ivory Violet

1992.    To Dye Ivory Violet. Dye red, and afterwards blue; or place the ivory in a highly-diluted solution of tin, and boil in the logwood bath..

1993. Aniline Dyes for Ivory

1993.  Aniline Dyes for Ivory. Any of these colors give a fine and permanent color to ivory by immersion.

1994. To Make Ivory Flexible

1994.    To Make Ivory Flexible. Ivory is rendered flexible by immersion in a solution of pure phosphoric acid (specific gravity 1.13) until it loses, or partially loses its opacity, when it is washed in clean cold water, and dried. In this state it is as flexible as leather, but gradually hardens by exposure to dry air. Immersion in hot water, however, restores its softness and pliancy. The following method may also be employed: Put the ivory to soak in 3 ounces nitric acid mixed with 15 ounces water. In 3 or 4 days the ivory will be soft.