  First results of an analysis to determine contribution of decays of the
unstable $^{8}$Be and $^{9}$B nuclei and the Hoyle 3$\alpha$-state to
dissociation of $^{14}$N $\to$ 3He (+H) are presented. As the research
material, layers of nuclear track emulsion longitudinally exposed to 2.9 $A$
GeV/$c$ $^{14}$N nuclei with at the JINR Nuclotron. Under the assumption that
the He and H fragments retain momentum per nucleon of the primary nucleus,
these unstable states are identified by the invariant mass calculated from the
emission angles of the fragments.
