This hole contains a solution of potash; for the alkali being extremely soluble, disappears in the water at the instant it is produced. Its presence, however, may be easily ascertained, alkalies having the property of changing paper, stained with turmeric, to a red colour; if you dip one end of this slip of paper into the hole in the ice you will see it change colour, and the same, if you wet it with the drop of water in which the first piece of potassium was burnt.
CAROLINE.
It has indeed changed the paper from yellow to red.
MRS. B.
This metal will burn likewise in carbonic acid gas, a gas that had always been supposed incapable of supporting combustion, as we were unacquainted with any substance that had a greater attraction for oxygen than carbon. Potassium, however, readily decomposes this gas, by absorbing its oxygen, as I shall show you. This retort is filled with carbonic acid gas.—I will put a small piece of potassium in it; but for this combustion a slight elevation of temperature is required, for which purpose I shall hold the retort over the lamp.
CAROLINE.
Now it has taken fire, and burns with violence! It has burst the retort.
MRS. B.
Here is the piece of regenerated potash; can you tell me why it is become so black?
EMILY.