I've seen this can around before.  I'm sure it was my great grandfathers, but not positive.  Any idea on when and a what it was used for?  Only writing on it is 'patent applied' stamped on the bottom.  Mom had it stashed in a corner and came across it again.

It's a tobacco tin. There are very similar if you search "justrite tobacco tin"

 

Good place to keep your welding flux.

Curved so it would sit well in a back pocket. (Like a "hip flask".)

if your great grandfather had any connection with mining industry it could be a container to carry calcium carbide for a carbide (actylene) lamp during a shift in the mine.

"By hammer and hand all arts do stand."

Thanks guys.  tobacco container it is.