Coprecipitation of radium with precipitates composed of polyethylene glycol — metal(II) salts of heteropolyacids has been
described. The calcium salt of phosphomolybdic acid, precipitated in the presence of polyethylene glycol (m. wt. 1000) has
been chosen for the more detailed study of radium coprecipitation. The influence of acidity, amount of precipitate, concentration
of calcium cations and of polyethylene glycol on radium coprecipitation has been determined. On the basis of the results obtained,
suitable conditions for quantitative concentration of radium from aqueous solutions have been found. The described method
of radium concentration can be used for determination of radium in aqueous samples.