  Recently, E.Feigin introduced a very interesting contraction $\mathfrak q$ of
a semisimple Lie algebra $\mathfrak g$ (see arXiv:1007.0646 and
arXiv:1101.1898). We prove that these non-reductive Lie algebras retain good
invariant-theoretic properties of $\mathfrak g$. For instance, the algebras of
invariants of both adjoint and coadjoint representations of $\mathfrak q$ are
free, and also the enveloping algebra of $\mathfrak q$ is a free module over
its centre.
