  For a double solid $V\to P_3(C)$ branched over a surface $B\subset P_3(C)$
with only ordinary nodes as singularities, we give a set of generators of the
divisor class group $Pic(\tilde{V}})$ in terms of contact surfaces of $B$ with
only superisolated singularities in the nodes of $B$. As an application we give
a condition when the integral cohomology of $\tilde{V}$ has no 2-torsion. All
possible cases are listed if $B$ is a quartic surface. Furthermore we give a
new lower bound for the dimension of the code of $B$.
