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An original bottle of "rotten stone" from the Daguerreian era.
National Gallery of Canada, The Origins of Photography: The Matthew R. Isenburg and Enhanced Isenburg Collections 1840-1880
Note that on the label it specifically says that the contents are for "Daguerrean Purposes".
Rotten stone, or rottenstone, is soft material resulting from the decomposition of siliceous limestone and was used to scour and polish the surface of a plate to remove surface imperfections prior to taking the exposure.
Other materials used for polishing were rouge and chimney black (soot).