eggshels

Updated: May 9, 2025

And so we see that not only other Vegetable substances, but even White woods, as the Hazel, will yield a Black Charcoal, and afterwards Whitish ashes; And so Animal substances naturally White, as Bones and Eggshels, will grow Black upon the being Burnt, and White again when they are perfectly Calcin'd.

Robert Boyle - Experiments and Considerations Touching Colours (1664)