PURPOSE: To eliminate the froth generated in a vial during dissolving operation of a protein prepn. without generating leakage at the time of the dissolving operation and to check the leakage in the vial.

CONSTITUTION: This liquid communicating tube is formed by connecting pricking needles 2, 3 respectively to both ends of a tube 1. Both of the pricking needles 2, 3 have liquid chemical passages 21, 31 and gas passages 22 communicating with vent ports 23 in their longitudinal direction. These vent ports 23 are internally provided with sterilizing filters 24. The vent port 23 of the one pricking needle 2 is hermetically closed freely openably by a cap 25 as a closing member. Interposing of a clamp in the tube 1 is equally permitted.