An improved titration medium for sulphate-ion indicators

The indicators sulphaonazo III, dimethylsulphonazo III and carboxyarsenazo have been compared for the determination of sulphur by flask combustion or by furnace-tube combustion. Carboxyarsenazo is preferred, the optimum conditions for its use being a 2 + 1 acetone-water solution buffered with pyridine and perchloric acid.