The Protean Liquid.
A red liquor, which, when poured into different glasses, will become yellow, blue, black, and violet, may be thus made: Infuse a few shavings of logwood in common water, and when the liquor is red, pour it into a bottle; then take three drinking-glasses, 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 newly washed, and leave the third without any preparation. If the red liquor in the bottle be poured into the first glass it will assume a straw color; if into the second, it will pass gradually from bluish-gray to black, provided it be stirred with a bit of iron, which has been privately immersed in good vinegar; in the third glass the red liquor will assume a violet tint.