The Alchemist’s Ink.
Dissolve in water a small quantity, about as much as will lay on a ten-cent piece, of chloride of cobalt, which is of a bluish-green color, and the solution will be pink; write with it and the characters will scarcely be visible; but if gently heated they will appear in brilliant green, which will disappear as the paper cools.
Dissolve in water a few grains of prussiate of potash; write with this liquid, which is invisible when dry; wash over with a dilute solution of iron, made by dissolving a nail in a little aqua fortis; a blue and legible writing is immediately apparent.
Chameleon Liquids.
Put a small portion of the compound called mineral chameleon into several glasses. Pour upon each water at different temperatures and the contents of each glass will exhibit a different shade of color. A very hot solution will be of a beautiful green color; a cold one a deep purple.
Make a colorless solution of sulphate of copper; add to it a little ammonia equally colorless, and the mixture will be of an intense blue color; add to it a little sulphuric acid, and the blue color will disappear; pour in a little solution of caustic ammonia, and the blue color will be restored. Thus may the liquor be changed at pleasure.