The materials needed are: One glass pitcher,
filled with water, four glass tumblers, an acid, an alkali and
some phenolphthalein solution which can be obtained from your
local druggist. Before the performance, add a few drops of the
phenolphthalein to the water in the pitcher and rub a small
quantity of the alkali solution on the sides of two of the
tumblers and repeat, only using as large a quantity of the acid as
will escape notice on the remaining tumblers. Set the tumblers so
you will know which is which and proceed as follows: Take hold of
a prepared tumbler with the left hand and pour from the pitcher,
held in the right hand, some of the liquid. The liquid turned into
the glass will become red like wine. Set this full tumbler aside
and take the pitcher in the left hand and pour some of the liquid
in one of the tumblers containing the acid as it is held in the
right hand. There will be no change in color. Repeat both parts in
the same order then begin to pour the liquids contained in the
tumblers back into the pitcher in the order reversed and the
excess of acid will neutralize the alkali and cause it to lose its
color and in the end the pitcher will contain a colorless liquid.
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