They spread outward in every direction to regions where they are in low concentration. Your nose is able to detect the smell of the cologne or perfume even if you are quite a distance from the bottle that has been opened. Diffusion occurs in all states of matter: solid, liquid, and gas.
enclave, exclave - An enclave is a group or area different from the surroundings, a secured area within another secured area, from Latin clavis, key; an exclave is the same thing, but usually describes a portion of a country separated from the main part and surrounded by politically alien territory.
The Enclave is a nation state established after the Great War, formed by members of the pre-War United States government and military industrial complex. It claims authority over the territory of the United States of America, considering itself the legal continuation of the U.S. government and styling itself as such.