“…Dilute solutions of protein can be concentrated by electromigration (384) • One apparatus for carrier-free continuous electrophoresis (542) yields impure fractions of serum proteins (453). Continuous-electrophoresis apparatuses have been designed to use polyacrylamide gels (117,507) or a thin gelatin plate (1260). A preparative apparatus (1018) uses the Preetz countercurrent principle [cf.…”