Final answer:
The invisible man uses a potent cosmetic capable of altering complexion to affect his appearance before retiring.
Step-by-step explanation:
The invisible man applies a potent cosmetic before he retires. This substance has the ability to affect the complexion, as evidenced by the excerpt suggesting that it could wash away freckles or even 'take the blood out of the cheek'. It's a powerful concoction that is indicative of the theme of vanity and alteration of natural appearance in literature.