Bulk superconductivity in Bi4O4S3 revealed by specific heat measurement
  Specific heat experiments on a well-characterized polycrystalline sample of the BiS2 based superconductor Bi4O4S3 revealed that it shows a crear specific heat anomaly at about Tc = 4.4 K, consistent with Tc from the resistivity and dc susceptibility. This observation indicates the superconductivity of Bi4O4S3 to be bulk in nature. 
Hiroshi Takatsu, Yoshikazu Mizuguchi, Hiroki Izawa, Osuke Miura, and   Hiroaki Kadowaki
cond-mat.supr-con cond-mat.str-el