Thing? above the dimmer switch??

Well, LOL it's what becomes of being "old." First one of these I ever saw was when I became concious of the world, perhaps 4 or 5 (So about 1953). We had about a 50--51 Ford which had one. Back then most? all? of em were aftermarket, not factory, and had GLASS!!!! jugs. They also had a snap in bracket which held a smaller 1 pint or so GLASS!!! bottle with concentrate detergent

This one here is "fancy" it is vacuum pump operated, still glass, LOL






Wait, just wait, until you discover your first oil bath air filter LOL