run something into something. 1. to guide or route something, such as a wire or a pipe, into something or a place. The worker ran the circuit into each room. He ran in the circuit as specified. 2. to guide something into something; to drive or steer something into something else.
A change of color to a blue-black or purple color suggests that starch is present. If there is no change in color, this suggests no starch is detectable. Note the change of the iodine to black on the potato (right) but not the apple (left). (10% Tincture of iodine.) Potato contains starch, but apple does not.
Iodine stains starch because of the chemical reaction between it and the polysaccharides in starch molecules. This reaction turns the starch a deep blue hue. This phenomenon is called Lugol's reaction for starch. Iodine is useful in laboratories and medical offices because it also reacts with many other compounds.