The field-induced gap observed in the specific heat of Yb4As3 is interprete
d as being due to the effective staggered field introduced hy the alternati
ng g-tensor and alternating Dzyaloshinsky- Moriya interactions. This mechan
ism also provides a natural explanation for the anomalous increase of magne
tic susceptibility at low temperatures. A specific prediction is made for t
he dependence of the gap on the field direction.