Pyrex glass electrical resistivity

Of the three commonly available types of glasses, borosilicate (Pyrex-type) glasses appear to be the most satisfactory. They combine the properties of good electrical resistance, resistance to thermal shock, and mechanical... 

Fabricated from Pyrex glass capillaries by pulling. The tips are beveled to reduce the electrical resistance while conferring sharpness to enable penetration of cell walls. 

Fig. 3.12. Specific electrical resistivity of a Pyrex-type glass (1), Neutral-glass 4.9 (2), alkaline free Alumo-Boro-Silicate glass (3), E-fiber glass (4) and an alkaline poor Alumo-Boro-Silicate glass (5) melt as function of the temperature [486]...

The dimensions and properties of the lamp envelope are based on the discovery that the volume of Hg is critical for effective UV operation [50]. Higher Hg pressures result in the need to use higher microwave power levels. To focus the MW field efficiently into the EDL, a special Cd low-pressure lamp with a metal antenna (a molybdenum foil) was developed for experiments in MW-absorbing liquids [51]. The envelope material must be impermeable to gases, an electrical insulator, and chemically resistant to the filling compounds at the temperature of operation. High quality quartz is the most widely used lamp envelope material but early manufacturers of EDL used glass, Vycor, or Pyrex [52]. 

---