isoprophlex parent
What these early chemists accomplished with, to our eyes, extremely crude methods is astounding. Physical methods like weighing, burning and collecting residue; describing crystallization and precipitation behavior, even smelling (and sometimes tasting) was at one point a routine thing to do.
The story of how Oxygen was discovered was super interesting and involved all of these methods.
Argon is an interesting one. A comparison between chemically synthesised nitrogen and ‘pure’ nitrogen extracted from the air (with the oxygen, carbon dioxide and water removed) revealed a discrepancy:
https://en.wikipedia.org/wiki/Argon#History
https://www.youtube.com/watch?v=loqudG71uBM (Chemistorian, noble gases)
Wow. Pre that discovery what did they think explained phonomenon like snuffing out a candle. Or blowing air on a fire.