AbstractAs a continuation of an earlier paper concerned with the viscosity of aqueous solutions of NaCl and KCl, the present paper communicates the results of precise, relative measurements of the viscosity of aqueous solutions of CaCl2. The measurements covered the entire range of composition up to saturation, all at atmospheric pressure and at 20.00, 25.00, 30.00, 40.00, and 50.00°C ± 0.01°C. The reproducibility was of the order of several parts per ten thousand, and the accuracy is estimated to be one of 0.3% at worst. ‐ As a byproduct, we obtained an accurate correlation between molality,c, and density,p, for these solutions measuring at 20.00 and 25.00°C (± 0