Abstract: Microcapsules are made by (a.) dispersing or dissolving a core substance in a film-forming polymer solution, (b.) emulsifying in fine droplets the resulting dispersion or solution in a vehicle which is poorly miscible with the solvent of the polymer solution and which doesn't dissolve said polymer to prepare an emulsion, and (c.) adding to the emulsion a non-solvent for the polymer wherein the non-solvent is miscible with the solvent, poorly miscible with the vehicle, and does not dissolve the polymer, whereby the solvent is removed by being absorbed by non-solvent emulsion droplets to precipitate the polymer film around the core substance.

Abstract: Novel diacyl penicillins of the formula ##EQU1## wherein R is alkyl, cycloalkyl, aryl, aralkyl, phenoxyalkyl, heterocyclic carboxyl excepting isoxazole carboxyl derivatives, or ##SPC1##In which benzene ring A may optionally be substituted andB represents a protective group for the amino group, and X is a protective group for the carboxyl group, are produced by reacting a benzyl penicillin ester of the formula ##EQU2## wherein X is as defined above, with a chlorinating agent in the presence of tertiary organic base to obtain an imide chloride group-incorporated compound of the formula ##EQU3## and then reacting the compound of the last-named formula with carboxylate of the formulaR-COOM (IV)wherein M is a metal atom, and R is as defined above.