A method including mixing using a mixer a first component and a second component to form a liquid before supply to a space between the projection system and a substrate, measuring a property of the liquid using a measuring device and making the feedback available to a controller, based on the feedback, controlling with the controller a physical property of the liquid by controlling the amount of the first and/or second component used to form the liquid, supplying the liquid to the space between the projection system and the substrate, and projecting a patterned beam of radiation, using the projection system, through the liquid onto a target portion of the substrate.