  Results in the quenched approximation for SU(3) breaking ratios of the
heavy-light decay constants and the $\Delta F=2$ mixing matrix elements are
reported. Using lattice simulations at $6/g^2=5.7$, 5.85, 6.0, and 6.3, we
directly compute the mixing matrix element $M_{hl}=< \bar P_{hl}|\bar h
\gamma_\mu (1-\gamma_5)l \bar h \gamma_\mu(1-\gamma_5)l|P_{hl}>$. Extrapolating
to the physical B meson states, $B^0$ and $B_s^0$, we obtain $M_{bs}/M_{bd}
=1.76(10)^{+57}_{-42}$. in the continuum limit. The systematic error includes
the errors within the quenched approximation but not the errors of quenching.
We also obtain the ratio of decay constants,
$f_{bs}/f_{bd}=1.17(2)^{+12}_{-6}$. For the B parameters we find $B_{bs}(2
GeV)=B_{bd}(2 GeV)=1.02(13)$; we cannot resolve the SU(3) breaking effects in
this case.
