Indicators in fused salts

Abstract

Conventional organic indicators have been found to be stable and soluble in two dissimilar salt melts and to give colour changes in the presence of acidic and basic reagents very similar to those given in aqueous solutions. The similarity of colour was found to extend to the shape and position of the ultraviolet and visible absorption bands. A number of indicators were found to be useful in fused potassium thiocyanate though only phenolphthalein was satisfactory in fused lithium nitrate–potassium nitrate eutectic.