A chill tube made of copper for the continuous casting of metals has a multi-corner inner and outer cross section and a nominal wall thickness which amounts to 8% to 10% of the separation distance of the inner surfaces lying frontally opposite each other at the tube opening. According to the invention, said control device comprises a plurality of elements of a substantially transparent material, which are inserted in respective passages extending between said tank and the outside of the body of the dispenser. The differential mechanism distributes drive force that is inputted from the input shaft via the housing into a first output shaft and a second output shaft. The first and the second variation devices are controlled by a control valve which takes up a first control position upon a forward movement determined by the position of the operating lever and which takes up a second control position upon reverse movement determined by the operating lever.