MAREK MIS / SCIENCE PHOTO LIBRARY MAREK MIS / SCIENCE PHOTO LIBRARY
Tannic acid crystals. Polarized light micrograph of a section through crystals of tannic acid (tricarboxylic acid). Tannic acid is a commercial form of tannin, an astringent polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids. Magnification: x100 when printed at 10 centimetres tall.
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