The experimental device DCX-1 has, in the past, observed proton trapping resulting from Lorentz dissociation of H2+ which was formed from the dissociation of H3+ within a water vapor cell. This letter presents evidence for proton trapping resulting from Lorentz dissociation of H3+ itself, with the H3+ coming directly from a duoplasmatron ion source. The evidence rests upon a measurement of the proton loss rate, which is proportional to the trapping rate. At high pressures the trapping rate is proportional to the pressure, a characteristic of gas dissociation. At low pressures, however, the trapping rate approaches a constant, independent of the pressure. This indicates another trapping mechanism, Lorentz dissociation, which is independent of pressure.