A highly reproducible seeded crystal growth method is described
for the study of calcium carbonate and sulfate crystallization
reactions in which the solution composition is maintained
constant by the potentiometrically controlled addition of reagents ..
Both hydrogen and calcium specific ion electrodes may be used to
control the reactions and the rates are measured with a precision
hitherto unattainable even at very low supersaturations. For calcium
carbonate, the rate of crystallization is proportional to the
square of the relative supersaturation expressed in terms of the
activities of the free ion species. The inhibiting influence of a
phosphonate additive upon the rate of growth is discussed
