other alcohols is in the range of 0 1 10 0 1 by weight the ratio of the mixed solvent to crude edta 4na purity of 40 wt is in the range of 0 8 5 0 1 by weight the crystallization may be performed at 40 70 u00b0 c and preferably 50 70 u00b0 c the resulting crystals have a narrow distribution of particle size for example they contain less than 11 wt and preferably less than 10 wt of particles having a diameter less than 30 u03bcm the present invention will be described in more detail by way of various examples which should not be construed to limit the scope of the present invention the solubility of edta 4na in water was measured by varying the temperature from 20 u00b0 c to 60 u00b0 c the results are shown in fig1 as can be seen in fig1 the solubility of edta 4na in water is almost constant regardless of temperature this indicates that crystallization with temperature variation is not effective to obtain edta 4na crystals in water the solubility of edta 4na in an aqueous methanol solution was determined by varying the concentration of meoh in the range of 0 wt to 100 wt the results are shown in fig2 as shown in fig2 the solubility of edta 4na sharply decreases as the methanol concentration increases the solution 538 g containing about 40 wt of edta 4na obtained in.