The physical properties of the powder also give it a mild astringent action.
It has a sweet astringent taste, very soluble in water, but scarcely soluble in alcohol.
Iron in the intestine causes an astringent or constipating effect.
Calcium salts form insoluble soaps with fats, and combine with albumen in a manner which makes them soothing and astringent rather than irritating.
Soluble salts of manganese, aluminium, zinc, copper, gold, platinum and bismuth have, when given by the mouth, little action beyond their local astringent or irritating effects; but when injected into a blood vessel they all exert much the same depressing effect upon the heart and nervous system.