What is a white crystalline substance, C6H7(OH)5, found in acorns, the fruit of the oak (Quercus). It has a sweet taste, and is regarded as a pentacid alcohol called?

quercite — A white crystalline substance, C6H7(OH)5, found in acorns, the fruit of the oak (Quercus). It has a sweet taste, and is regarded as a pentacid alcohol. (Webster's 1913.)

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