1. A PROCESS FOR EXHAUST DYEING FROM A SINGLE BATH A FIBROUS MATERIAL CONTAINING A MIXTURE OF CELLULOSE FIBERS AND POLYACRYLONITRILE FIBERS WITH A REACTIVE DYESTUFF HAVING AT LEAST ONE VINYLSULFONE REACTIVE GROUP OR ONE GROUP THAT FORMS A VINYLSULFONE REACTIVE GROUP IN ALKALINE MEDIUM AND WITH A NON-REACTIVE BASIC DYESTUFF, WHICH COMPRISES HEATING SAID MATERIAL AT A TEMPERATURE BETWEEN ABOUT 20*C AND ABOUT 80*C IN AN AQUEOUS DYEBATH THAT CONTAINS SAID REACTIVE DYESTUFF, A NON-IONIC DISPERSING AGENT AND AND ALKALINE AGENT TO ADJUST THE PH OF SAID DYEBATH TO BETWEEN ABOUT 9 AND ABOUT 12 UNTIL SAID REACTIVE DYESTUFF IS FIXED ON THE CELLULOSE FIBERS, ADDING TO SAID DUEBATH SAID NON-REACTIVE BASIC DYESTUFF AND A FREE ORGANIC ACID OR INORGANIC ACID TO ADJUST THE PH OF SAID DYEBATH TO BETWEEN ABOUT 3.5 AND ABOUT 6, AND HEATING SAID MATERIAL IN SAID DYEBATH AT A TEMPERATURE BETWEEN ABOUT 95*C. AND ABOUT 130*C. UNTILS SAID BASIC DYESTUFF IS FIXED ON THE POLYACRYLONITRILE FIBERS.