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.