Aging effect of starting solutions on wet-chemical powder preparation using ethanolic solution of oxalic acid

When magnesium oxalate hydrates were precipitated by mixing ethanolic solut ions of the metal nitrates and oxalic acid with addition of water, particul ar attention was paid to the age of the starting solutions, which had drast ically influenced the precipitation behavior. For instance, the aging time of several days exponentially delayed the occurrence of the clouds in the s olution, in other words, elongated the incubation period of the precipitati on. Although the structural features in the aged solution have not yet been clarified by NMR, we believe that a visibly transparent solution is not al ways homogeneous, even if it looks stable for a long period.