  The dependence of the superconducting transition temperature T_{c} on nearly
hydrostatic pressure has been determined to 67 GPa in an ac susceptibility
measurement for a Li sample embedded in helium pressure medium. With increasing
pressure, superconductivity appears at 5.47 K for 20.3 GPa, T_{c} rising
rapidly to ~ 14 K at 30 GPa. The T_{c}(P)-dependence to 67 GPa differs
significantly from that observed in previous studies where no pressure medium
was used. Evidence is given that superconductivity in Li competes with symmetry
breaking structural phase transitions which occur near 20, 30, and 62 GPa. In
the pressure range 20-30 GPa, T_{c} is found to decrease rapidly in a dc
magnetic field, the first evidence that Li is a type I superconductor.
