Formulations contain (A) magnesium cpds. with a water solubility of less than 400 ppm in an amount corresponding to a magnesium conc. of 2-27 wt.%, and (B) 0.1-12 wt.% dispersing agent. Mg content is pref. 15-22 wt.%, and the concn. of dispersing agent is pref. 2-8 wt.%. Pref. Mg cpds. are magnesium oxide and magnesium hydroxide.
