Three different colours may be produced from the same infusion, merely
by the addition of three colourless fluids. Slice a little red cabbage,
pour boiling water upon it, and when cold, decant the clear infusion,
which divide into three wine-glasses: to one, add a small quantity of
solution of alum in water; to the second, a little solution of potash
in water; and to the third, a few drops of muriatic acid. The liquor
in the first glass will assume a purple colour, the second, a bright
green, and the third a rich crimson.
Put a dram of powdered nitrate of cobalt into a phial containing an
ounce of the solution of caustic potass; cork the phial, and the liquid
will assume a blue colour, next a lilac, afterwards a peach colour, and
lastly a light red.