  This is an old paper put here for archeological purposes. We derive a general
formula expressing the second homology of a Lie algebra of the form L\otimes A
with coefficients in the trivial module through homology of $L$, cyclic
homology of $A$, and other invariants of $L$ and $A$. This is achieved by using
the Hopf formula expressing the second homology of a Lie algebra in terms of
its presentation. We also derive a similar formula for the associated Lie
algebra of the tensor product of two associative algebras.
