Abstract: A vaporizing nozzle comprises a wall of porous material, for example sintered bronze, through which the liquid to be evaporated percolates. The liquid may be, for example, petrol. At the other side of the wall the liquid atomizes or vaporizes into a gas stream, for example an air stream. The nozzle therefore provides a simple and convenient way of vaporizing or atomizing a liquid within a gas stream in, for example, the vaporization of petrol into an air stream for use with internal combustion engines. The nozzle includes selectively closed machined portions for altering the flow characteristics of the material.