The general rule is that proof of delivery of goods to a bailee and the failure of the bailee to return them makes out a prima facie case and the burden of proof is then cast upon the bailee to provide evidence rebutting the inference of negligence. Catalfano v. Higgins, Del. Super., 56 Del. 136, 191 A.2d 330, 6 Storey 136 (1963). It is not enough to show that the bailed property was stolen, it must be establish that the theft was not occasioned by its negligent acts. If the evidence is conclusive that due care was exercised, the bailee must be found free from negligence as a matter of law. Catalfano v. Higgins, Supra.