Probably used in a telephone.Terry's got it right -- eg Columbia Dry Cell Battery -- see....
I suppose the shiny black material is an insulating/sealing glassy / ceramic material, or something tarry? Copper in the center electrode, corroding green -- perhaps you will find the location of the other electrode under the adhering muck on the other side?American Chemical Society: Chemistry for Life.www.acs.org
Pretty cool. 1 1/2 volts - I wonder what it might have powered back then -- might be interesting to better establish age --- that type top seems, on quick internet search, to date from as early as the 1890s.
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