  Vacuum tube with graphite. 
This seems to be an amplifier tube of some sort, why it has graphite electrodes I don't know.  The same source sent me another tube that contains loose beads of mercury, another thing you don't commonly see in vacuum tubes.  Not that you commonly see vacuum tubes of any sort these days. 
Source: Max Cane 
Contributor: Max Cane 
Acquired: 3 September, 2007 
Text Updated: 3 September, 2007 
Price: Donated 
Size: 5" 
Purity: >90%
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