What did Georges Lemoine’s hydriodic acid experiment show about catalysts and equilibrium?

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nanoparticles: hydrogen peroxide — catalysis Nanoparticles of a gold-palladium (yellow-blue) alloy supported on acid-treated carbon (gray) directly catalyzing hydrogen peroxide formation from hydrogen (white) and oxygen (red) while shutting off unwanted hydrogen peroxide decomposition.

In 1877, Georges Lemoine demonstrated that the decomposition of hydriodic acid into hydrogen and iodine reached the same equilibrium point (19 percent at 350 °C) regardless of whether the reaction proceeded slowly in the gas phase or rapidly in the presence of a platinum sponge catalyst.1

This experiment provided crucial evidence that catalysts do not alter the position of equilibrium in a chemical reaction. Furthermore, it established the important principle that a substance acting as a catalyst for a forward reaction must also catalyze the corresponding reverse reaction.1