  Trying to dope graphite flakes we found that the magnetization of pure,
several tens of micrometers grain size graphite powder and after a simple
treatment with pure water shows clear and reproducible granular superconducting
behavior with a critical temperature above 300K. The observed magnetic
characteristics as a function of temperature, magnetic field and time, provide
evidence for weakly coupled grains through Josephson interaction, revealing the
existence of superconducting vortices.
