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What chemical expirements did James Watt study?
Watt was very interested in chemistry.
In late 1786, while in Paris, he witnessed an experiment by Berthollet in which he reacted hydrochloric acid with manganese dioxide.

Question: was there a significant discovery when Berthollet reacted Hydrocloric acid with manganese dioxide?
Self-contained rewrite: was there a significant discovery when Berthollet reacted Hydrocloric acid with manganese dioxide?