🚀 go-pugleaf

While rumaging in a collection of old electronics parts (1940's-70's)
I found a device that is interesting and I wondered if it could be
identified.
It is a small black (bakelite, I believe) cylinder about 1cm diameter and
2cm long.  One end in closed except for a small hole that allows a wire
to exit, while the other end is open with internal threads.  In the threaded
end is a metal threaded plug with a central hole that also allows a wire to
exit this end.  Basically, it looks like an axial lead capacitor.  
The interesting part is inside.  When I unscrewed the threaded plug, I found
that under the plug was a spring compressing about twenty thin round metallic
plates together.  The plates are dark grey on one side, and the other side
looks like a cold solder joint (rough, crystalline, and shiny silver). 
This appears to be a mechanism that compresses twenty plates together and
connects a wire to each end of the stack.  My guess is some kind
of rectifier?
There are numbers on the outside of the case: OKV26  K2  6A6 Q
I'm really curious.  Does anyone know what this is?
Thanks in advance.
--keith