Abstract: A connector for a jack includes four contacts of first, second, third and fourth contacts each having a contact portion and a connection portion, and a housing, to exchange signals and to ascertain whether a plug connector has been inserted into the connector. The third contact substantially U-shaped in cross-section includes a contact piece having a first contact part adapted to contact the plug connector, and a spring piece having an elasticity facing to the contact piece and provided by forming a U-shaped slit in a part of the third contact at a location opposite to the contact piece. When the plug connector is inserted into the connector, the plug connector pushes the first contact part of the contact piece to cause the contact piece to be displaced to the spring piece so that the contact piece pushes the spring piece to cause the spring piece to be displaced toward the housing and at the same time the spring piece pushes the contact piece with each other with the aid of its elasticity.

Abstract: Disclosed is a process for preparing a polymer solution having a reduced unreacted unsaturated monomer content, comprising radically polymerizing at least one unsaturated monomer in a solvent in the presence of a radical polymerization initiator, the at least one unsaturated monomer having a lower boiling point than that of the solvent, wherein the weight ratio of the total amount of the unsaturated monomers to the solvent is from 1/9 to 7/3, the polymerization is carried out until the conversion of the unsaturated monomer having the lowest conversion of all the other unsaturated monomers whose boiling point is lower than that of the solvent reaches at least 85%, and, after completion of the polymerization, the reaction mixture is rectified to remove the unreacted unsaturated monomer or monomers.