aug 31, 1670 - Johann Becher and George Stahl (dominated during the 1670s through 1790s) - the Phlogistic theory- when you burned something it lost phlogiston in the air. A problem of the theory resulted in different masses when metals were burned. The problem was fixed by assigning negative masses to phlogistons.
Added to timeline:
Alyssa George, Riley Gloeckl, Grace Bair, Sonja Hebestreit