1. A FIRE-RESISTANT CELLULAR REACTION PRODUCT COMPRISING: (I) THE LIQUID RESINOUS REACTION PRODUCT OF (A) A HALOGEN-CONTAINING POLYHYDRIC ALCOHOL SELECTED FROM THE GROUP CONSISTING OF (1) THE REACTION PRODUCT OF HEXAHALOCYCLOPENTADIENE, WHEREIN THE HALOGEN IS SELECTED FROM THE GROUP CONSISTING OF CHLORINE, BROMINE, FLUORINE, AND MIXTURES THEREOF, AND A DIHYDRIC ALCOHOL CONTAINING ALIPHATIC CARBON-TO-CARBON UNSATURATION AND (2) THE REACTION PRODUCT OF DECACHLOROOCTAHYDRO-1,3,4-METHENO-2HCYCLOBUTA-(CD)-PENTALENE-2-ONE AND A POLYHYDRIC ALCOHOL CONTAINING AT LEAST THREE HYDROXYL GROUPS, AND (B) AN ORGANIC POLYISOCYANATE; (II) A HYDROXYL-CONTAINING POLYMERIC MATERIAL HAVING A HYDROXYL NUMBER OF BETWEEN THIRTY AND SIX HUNDRED AND FIFTY, SELECTED FROM THE GROUP CONSISTING OLF (A) A POLYESTER COMPRISING THE REACTION PRODUCT OF A POLYHYDRIC ALCOHOL AND A POLYCARBOXYLIC COMPOUND, (B) A POLYETHER COMPRISING THE REACTION PRODUCT OF A MONOMERIC, 1,2-MONOEPOXIDE AND A COMPOUND SELECTED FROM THE GROUP CONSISTING OF A POLYHYDRIC ALCOHOL AND A POLYCARBOXYLIC ACID, AND (C) MIXTURES THEREOF; AND (III) A FOAMING AGENT; SAID LIQUID REACTION PRODUCT BEING PRESENT IN AN AMOUNT SUFFICIENT TO PROVIDE NINETY TO ONE HUNDRED AND TEN PERCENT OF ISOCYANATO GROUPS WITH RESPECT TO THE TOTAL NUMBER OF HYDROXYL AND CARBOXYL GROUPS PRESENT IN THE HYDROXYL CONTAINING POLYMERIC MATERIAL AND THE FOAMING AGENT.