  The energies of the lowest $^2P_u$, $^4P_g$ and $2D_g$ states of the boron
atom are calculated with $\mu$hartree accuracy, in the basis of symmetrized,
explicitly correlated Gaussian lobe functions. Finite nuclear mass and scalar
relativistic corrections are taken into account. This study contributes to the
problem of the energy differences between doublet and quartet states of boron,
which have not been measured to date. It is found that the
$^2P_u\rightarrow^4P_g$ excitation energy, recommended in the Atomic Spectra
Database, appears underestimated by more than 300~cm$^{-1}$.
