A Thistle Tube is a type of lab device typically used by chemists to add liquid to an existing system of apparatus. It consists mostly of a shaft tube with a reservoir and funnel-like section at the top. The shaft tube is designed to permit penetration through a small hole present in some stoppers, thereby allowing the tube to be inserted into a vessel such as an Erlenmeyer flask.
A thistle tube is made of glass and is usually required in experiments involving semi-permeable membranes. Thistle tubes are also suitable for application in separation experiments.