AbstractUsing a buffered pyridine electrolyte, sulphur gives a regular polarographic wave suitable for its quantitative determination. A method based on this principle has been developed for the determination of ‘true’ free sulphur in rubber. The method has been compared with gravimetric and volumetric processes, and found to give slightly lower results than either of these, since sulphur combined in any form in the acetone extract is not included. It is particularly suited to routine replicate determinations as it is considerably quicker than older meth