In Peter A. Kellers book on page 24, the following info
is to be found:
To illustrate the extremes in materials that have been used for CRT
envelopes, almost every CRT lab has at one time or another fabricated a
"Coketron" made from that one glass envelope that always seemed
to be present in any lab, the Coca-Cola™ bottle. A little phosphor
settled in the bottom and an electron gun sealed to the neck results in an
operable CRT that never ceases to amuse lab visitors.