Koter et al. (1997) for the details of the adopted atomic models). The iron-group elements, which are important for the radiative driving and consequently for $\dot{M}$, are treated in a generalized version of the “modified nebular approximation” (Lucy 1987, 2001, see also Schmutz 1991). We include Fe ionization stages up to [ix]{}, and we note that the first 30 elements of the periodic table are all included in the Monte Carlo computations for the line force. Although the cumulative effect of all these species on the radiative acceleration is properly included in our models, we will particularly highlight the roles of CNO, the dominant intermediate mass elements, and Fe, the dominant heavy metal.

As we wish to investigate the effect of a different chemical environment on the mass-loss rate of WR stars, we exclude the self-enriched element of carbon in WC stars, from what we call “$Z$”. Therefore, where we address the  – $Z$ dependence in WC stars, we mean a scaling with for instance the Fe abundance, realizing that the overall WR metal content is much larger (because of the large amounts of carbon produced by the WC stars themselves). Where we vary the Fe abundance, we also scale 