We shall study geometric
properties of the harmonic Lip1-capacity κ′n(E), E ⊂Rn. It is related to
functions which are harmonic outside E and locally Lipschitzian everywhere. We
shall show that κ′n+1(E × I) is comparable to κ′n(E) for E ⊂ Rn and for
intervals I ⊂ R. We shall also show that if E lies on a Lipschitz graph, then
κ′n(E) is comparable to the (n − 1)-dimensional Hausdorff measure ℋn−1(E).
Finally we give some general criteria to guarantee that κ′n(E) = 0 although
ℋn−1(E) > 0.