The Phlogiston Theory was a disproved and outdated theory that was stated in 1667 by German alchemist Johann Becher. The theory speculated that Phlogiston was a highly flammable element, which was released during combustion. The theory was named after the supposed element of Phlogiston. The theory stated that flammable substances contained a high concentration of ‘Phlogiston’, and lost it when they were burned. This theory was eventually disproved when experiments confirmed that certain metals such as Magnesium actually gained weight when they burned, negating the idea that objects always lost mass as they were heated.
As the group escaped Isla Sorna, Dr. Jack Thorne mentioned Phlogiston in his closing summary of how science changed and evolved over time.
The Lost World by Michael Crichton page 417 (First Edition, Thirty Fourth printing)