1.   The gas is ignited by an electrical spark.

2.   A. Lightning is the electrical spark set off when negative charges in thunderclouds move toward postive charges on theground or in other clouds.

3.   Corry said tests were being done to see if the nylon flock fibers at mill concentrations could be ignited by static electricity or an electrical spark.

4.   The NTSB believes the center fuel tank exploded, apparently because of an electrical spark.

5.   The safety board said an electrical spark of unknown origin inside the tank likely ignited the fuel vapors.

6.   The tank ruptured and spilled fuel, which was subsequently ignited by an as-yet unidentified electrical spark, causing a massive fire.

7.   There is a Tesla coil, which crackles with electrical sparks, and an exhibit that explains pulsars.

8.   They agree that a lightning bolt is a giant electrical spark that connects positive and negative electrical charges within a thunderstorm.

9.   They argued that it resulted from an electrical spark from a defective auxiliary fuel pump, though they had no direct evidence to support that theory.

10.   They suggested an electrical spark set off a dust explosion that swept across two production lines.