What is the process by which anything becomes of the color of a lemon; esp., in alchemy, the state of perfection in the philosopher's stone indicated by its assuming a deep yellow color. Thynne called?

citrination — The process by which anything becomes of the color of a lemon; esp., in alchemy, the state of perfection in the philosopher's stone indicated by its assuming a deep yellow color. Thynne. (Webster's 1913.)

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