Thyrite
Thyrite is a formerly trademarked name for a nonlinear, voltage-dependent resistive material introduced by General Electric in 1930. Consisting primarily of silicon carbide mixed with a ceramic binder,
It is physically similar to dry process porcelain and it can be made in any shape that can be successfully moulded.
[The material] does not follow Ohm's law, for each time the voltage is doubled the current increases 12.6 times. The ratio of change of current to change in voltage is constant over ranges of current of 10,000,000 to one. This means the resistance decreases as the current and voltage increase. The resistance at any particular value of voltage or current is fixed by the physical dimensions of the piece. It is slightly lowered at high temperatures but returns to normal when cooled. The resistance does not depend upon the rapidity of current or voltage change and it is unaffected by long service. Because of these definite characteristics of thyrite the action of lightning arresters can be accurately calculated for the first time.
Thyrite, A New Material for Lightning Arresters. In: Transactions of the American Institute of Electrical Engineers (Volume 49 Issue 2, April 1930)