Abstract: A wick assembly (1) for use in e.g. an anaesthetic vaporizer (not shown) comprises layer (2) of absorbent wick material, e.g. a metallic wire cloth, secured to an impermeable backing sheet (3) e.g. of stainless steel. The wick material (2) and backing sheet (3) are rolled into a spiral configuration and thus define a spiral flow passage for gas to be vaporized. Fastening means are provided to hold the wick material (2) and sheet (3) in the spiral configuration whereby the assembly forms a self-contained unit adapted to be detachably mounted in a vaporizer.