Magical Transmutations
Infuse a few shavings of logwood in common water, and when the liquor
is sufficiently red, pour it into a bottle. Then take three
drinking-glasses, and rinse one of them with strong vinegar; throw
into the second a small quantity of pounded alum, which will not be
observed if the glass has been recently washed, and leave the third
without any preparation. If the red liquor in the bottle be poured
into the first glass, it will appear of a straw colour; if into the
second, it will pass gradually from bluish-grey to black, when stirred
with a key, or any piece of iron, which has been previously dipped in
strong vinegar. In the third glass, the red liquor will assume a
violet tint.