dialysis

dialysis, in chemistry, separation of suspended colloidal particles from dissolved ions or molecules of small dimensions (crystalloids) by means of their unequal rates of diffusion through the pores of semipermeable membranes. This process was first employed in 1861 by a British chemist, Thomas Graham. If such a mixture is placed in a sack made of parchment, collodion, or cellophane and suspended in water, the ions and small molecules pass through the membrane, leaving the colloidal...