Abstract: Disclosed is a processing solution used for making lithographic printing plates by silver complex diffusion transfer process which contains at least one thioether derivative represented by the following formulas (I), (II) and (III): ##STR1## wherein n.sub.1 and n.sub.2 each represents 0, 1 or 2 and R.sub.1 and R.sub.2 each represents an alkylene group of 1-5 carbon atoms, ##STR2## wherein R.sub.1 represents an alkylene group of 1-5 carbon atoms, X represents a hydrogen atom, a carboxy group, an alkoxycarbonyl group, a carbamoyl group, a hydroxy group, or --OR.sup.2 in which R.sup.2 has the same meaning as --R.sub.1 --S).sub.n CH.sub.2 CH.sub.2 OH above, and n represents 0, 1 or 2, ##STR3## wherein X' represents an aromatic or heterocyclic group which has a carboxy group, R.sub.1 and R.sub.2 each represents an alkylene group of 1-5 carbon atoms and n represents 0, 1, 2 or 3.

Abstract: Disclosed is a process for producing a liquid developer for electrostatic photography which comprises a highly insulating hydrocarbon medium and resin particles dispersed therein, said process comprising polymerizing a monomer (A) soluble in said medium, but insolubilized upon being polymerized in the presence of a polymer (S) insoluble in said medium and having a carboxyl group, a hydroxyl group or an amide group. In this process, a monomer (B) soluble in said medium and still soluble upon being polymerization and/or a monomer (C) having at least two polymerizable unsaturated double bonds may also be polyumerized.