Wilhelm (Friedrich Philipp) Pfeffer

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Wilhelm (Friedrich Philipp) Pfeffer

1845-1920

German botanist who studied osmotic pressure. While working on cell metabolism, Pfeffer developed a semipermeable membrane with which he studied osmosis. In addition to creating a method for measuring osmotic pressure, he proved that osmotic pressure depends on the size of those molecules too large to pass through the membrane. In so doing, he was able to measure the size of giant molecules.

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