The relationship between drop size and location in an agitated liquid-liquid system was investigated, with a new sampling method in which the dispersion was sampled i n a specially designed trap and immediately encopsulated by a polymer film. The liquid-liquid system used was water and a mixture of isooctane and carbon tetrachloride with a density close to that of the water. Dispersed phase holdup was varied from 0.025 t o 0.34 volume fraction.For this system, which has low mutual solubility and high interfacial tension, there is almost no dependence of drop size on location for the mixing geometries studied. This was due to the fact that the coalescence rate is low compared to the circulation time. An increase i n impeller speed and drop size decreased the coalescence rate while an increase i n holdup increased it.The mean drop diameter was related to the Weber number and holdup by an equation. By comparison of mean drop diameters obtained using different impellers, it was shown that the criterion of equal power per volume can be used for estimating drop size when going from one mixing geometry to another, not too different, geometry a t moderate impeller speeds.When two mutually insoluble liquids are mixed in an agitated vessel, a dispersion of one phase can be produced in the other continuous phase. Turbulent fluctuations and viscous friction produce forces that tend to breakup the droplets whereas collision between two drops may result in their coalescence into a larger drop. Agitation maintained under constant conditions will result in dynamic equilibrium between the coalescence and breakup processes and appropriate sampling and measurement techniques can be used to determine the size and size distribution of the drops.A number of investigators have presented equations that relate drop size to mixing parameters and to the physical properties of the liquid system (I, 2, 11, 16, 19, 2 2 ) . Some of the equations relate the mean drop diameter in the vessel to the Weber number and to a hold-up function that represents the secondary effect of the coalescence mechanism. Drop size distribution caused by breakup alone was investigated for mixing vessels for pipes ( 4 ) . Each investigator found a different distribution function suitable to describe his data. It can be said that no general correlation is available at present for the drop size distribution function. Also, the results of studies of single drop breakup (8, 17, 2 0 ) differ to an extent not fully explained as yet. Divergent results have also been obtained in measurements of coalescence rates in liquid-liquid dispersions due to the different experimental techniques employed (5, 6, 7 ) . Sprow (19) and Vanderveen ( 2 1 ) studied variation of local mean drop diameter throughout the vessel. They have shown that drop sizes vary in the vessel according to the general model of a circulation path that involves breakup near the impeller followed by continuous coalescence along the circulation path. DROP SIZE MEASUREMENTS BY ENCAPSULATIONDrop sizes have been dete...

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The immunological methods for quantitating C3d in plasma require first the removal of less fragmented intermediates as well as the intact C3. We describe an alternative method for the quantitation of C3d in human plasma. The components which should be removed are absorbed (precipitated) directly in the plasma by a specific anti‐C3c antiserum. It is then possible to determine the concentration of C3d by routine immunological methods.