  We measure the scaling properties of the probability distribution of the
smoothed density field in $N$-body simulations of expanding universes with
scale-free initial power-spectra, with particular attention to the predictions
of the stable clustering hypothesis. We concentrate our analysis on the ratios
$S_Q(\ell)\equiv {\bar \xi}_Q/{\bar \xi}_2^{Q-1}$, $Q \leq 5$, where ${\bar
\xi}_Q$ is the averaged $Q$-body correlation function over a cell of radius
$\ell$. The behavior of the higher order correlations is studied through that
of the void probability distribution function.
  As functions of ${\bar \xi}_2$, the quantities $S_Q$, $3 \leq Q \leq 5$,
exhibit two plateaus separated by a smooth transition around ${\bar \xi}_2 \sim
1$. In the weakly nonlinear regime, ${\bar \xi}_2 \la 1$, the results are in
reasonable agreement with the predictions of perturbation theory. In the
nonlinear regime, ${\bar \xi}_2 > 1$, the function $S_Q({\bar \xi}_2)$ is
larger than in the weakly nonlinear regime, and increasingly so with $-n$. It
is well-fitted by the expression $S_Q= ({\bar \xi}_2/100)^{0.045(Q-2)}\
{\widetilde S}_Q$ for all $n$. This weak dependence on scale proves {\em a
small, but significant departure from the stable clustering predictions} at
least for $n=0$ and $n=+1$. The analysis of $P_0$ confirms that the expected
scale-invariance of the functions $S_Q$ is not exactly attained in the part of
the nonlinear regime we probe, except possibly for $n=-2$ and marginally for
$n=-1$. In these two cases, our measurements are not accurate enough to be
discriminant.
