Re-analysis of some bubble chamber data on $N \bar{N}$ annihilation

A re-analysis of some $\bar{p}p$ and $\bar{p}n$ data, at rest and in flight, obtained in bubble chamber experiments, is presented. The ($\pi ^{+}\pi ^{-}$) and ($K_{S}K_{S}$) final states for the channels (2$\pi ^{-}\pi ^{+}$) and ($K_{S}K_{S}\pi$) are investigated. Evidence for a narrow meson resonance structure, cautiously suggested as $f_{0} (1500)$, is given. In the ($\pi ^{+}\pi ^{-}$) invariant mass distribution from $\bar{p}n$ annihilations in flight, using the method of difference spectra, a very clear evidence for $\rho ^{0}, f_{2}(1270)$ and $f_{0} (1500)$ is first time obtained from these data. This re-analysis suggests that the old bubble chamber data can still provide relevant information on the annihilation process in liquid hydrogen and deuterium, and can elucidate controversial aspects of the annihilation mechanism.