  We calculate tractable microscopic expressions for the low-shear
normal-stress coefficients of colloidal dispersions. Although restricted to the
low rate regime, the presented formulas are valid for all volume fractions
below the glass transition and for any interaction potential. Numerical results
are presented for a system of colloids interacting via a hard-core attractive
Yukawa potential, for which we explore the interplay between attraction
strength and volume fraction. We show that the normal-stress coefficients
exhibit nontrivial features close to the critical point and at high volume
fractions in the vicinity of the reentrant glass transition. Finally, we
exploit our formulas to make predictions about rod-climbing effects in
attractive colloidal dispersions.
