Heat-sensitive copying-paper

Claim 1

A HEAT-SENSITIVE COPY-SHEET USEFUL IN PROVIDING DENSE DARK-COLOURED IMAGE AREAS OF PLEASING APPEARENCE IN THE THERMOGRAPHIC COPYING OF DIFFERENTIALLY RADIATION-ABSORPTIVE GRAPHIX ORIGINALS, SAID COPY-SHEET INCLUDING A VISIBLY HEAT-SENSITIVE LAYER COMPRISING: A NORMALLY SOLID ORGANIC ACID SALT OF A NOBLE METAL; A CYCLIC ORGANIC REDUCING AGENT FOR THE NOBLE METAL IONS, WHICH REDUCING AGENT HAS AN ACTIVE HYDROGEN FROM ATTACHED TO AN ATOM, SELECTED FROM THE CLASS OF OXYGEN, NITROGEN AND CARBON ATOMS, DIRECTLY ATTACHED TO AN ATOM OF THE CYCLIC RING; AND, AS A THIRD SIGNIFICANT COMPONENT AND IN SIGNIFICANT SMALL AMOUNT WITHIN THE APPROXIMATE PROPORTIONS OF ONE TO TEN PERCENT OF THE COMPOSITION, AN ORGANIC CARBOXYLIC ACID TONER COMPOUND HAVING A CARBOXYL GROUP AND AT LEAST ONE OTHER GROUP, FROM THE CLAS CONSISTING OF CARBOXYL AND HYDROXYL GROUPS, IN POSITION TO PERMIT CONDENSATION REACTION WITH SAID CARBOXYL GROUP AND WTIH FORMATION OF A HETERCYCLIC RING STRUCTURE HAVING 5-6 MEMBERS IN SAID RING.