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.
You could demonstrate the effect of iodine solution on starch by adding a few drops of solution to a starch powder or starch suspension in a boiling tube. You can then discuss the fact that this colour change might be hard to see in a dark green leaf until the chlorophyll is removed.