PURPOSE: To rationalize both the liquid temperature control and the transfer work of the nitric acid by jetting the pressed air into the nitric acid along with the flow of the Braun tube, and also to have highly efficient errosion for the junction part via the frit glass.

CONSTITUTION: Valve 21 of the Braun tube is floated in tank 11 into which the nitric acid 12 is put and then flown in a fixed direction, and at the and at the same time the temperature of nitric acid 12 is increased gradually toward the flowing direction of valve 21. Also, the pressed air is jetted (18) into the nitric acid along with the flow of the Braun tube. As a result, both liquid temperature control and the transfer work can be rationalized for the nitric acid, and at the same time the highly efficient errosion can be ensured for the junction part.