Extinction E(B − V) vs. polarization p for the clouds CB3, CB25, and CB39 for R_V = 3.1 and 4.0 are shown. The dashed line in the figure represents the error-weighted least-square linear fit with p as independent variable, to the data points in Tables 1–3, considering the errors in both variables. The “error bars” shown in the figures represent errors in p (taken from Sen et al. 2000) and errors in E(B − V) as derived in the present work.