Ten minutes later he lit a cigarette, which ignited gas from the spray and caused a huge explosion.

A ventilation system he designed a century ago allowed the blaze to spread after a projector ignited gases from expanding foam used in a student project.

The cause of that blaze was later found to be a projector that had ignited gases from expanding foam used in a student project.

It stated that smoking, sparking of electrical equipment, or frictionally ignited gas are among the probable igniting sources.

He used the brine and an area of shale that seeped an odorless, easily ignited gas to dry the salt.