Is it Euykral? (not sure if the spelling is correct). It was a white powder which came in a tin about 40 years ago. Haven't seen it for ages so not sure if it's still manufactured.
Eukryl (or however it's spelt) is still available as a smoker's toothpaste. Good chemists and Tesco stock it in tube form. It's in a white box with a green pattern. Never used it so I don't know what it tastes like tho.