The invention relates to a syringe comprising a cylindrical container (1) in which is arranged at least a first piston (5, 5a-b) which delimits a storage volume. The syringe is provided with at least one yielding element (16a-b) having a first side that delimits the storage volume in a liquid tight fashion, and having a second side that is in communication with the surroundings of the syringe. This renders the syringe liquid tight even if the pressure of the substance in the storage volume increases. This may be used when sterilizing with heat or when freeze drying substance in the syringe. In one embodiment the syringe comprises a first (5a) piston with a first piston rod (12) and a second piston (5b) with a second piston rod (13). The two pistons then define two storage volumes which may be used for storage of freeze dried substance and a solvent for the freeze dried substance, respectively. The different substances are unequally affected by heat sterilization, which may give rise to a pressure difference between the storage volumes, but the yielding element compensates for this such that no leaks between them occur.
