What element is in the tube? That is a great question. It turned out to be Mercury... (as in Alchemy - the Art of Egypt)
Also, it is really not that difficult to seal/pinch off the neck of a glass bottle, assuming you have the technology to make a glass bottle in the first place, and create a low pressure envelope inside. Glass blowers do it all the time.
And these gases ionize easily at room temperature - when you apply a high voltage AC (alternating current) electricity - and it works right through the glass - no electrodes required.
Post Edited (11-May-14 10:11)
(Electrical) Storms, Soap Bubbles and Solitons. - Cashus the Giant