A system of chemical notation was "invented" in 1811 by Jons Jakob Berzelius. His system was based on the "law of definite proportions", stating that all samples of a given chemical compound have the same elemental composition.

	Joseph Louis Proust actually published a paper stating the law of definite proportions in 1794, but it was not widely accepted until Berzelius added his support to the idea.

The Law of Definite Proportions: in a pure compound, the elements combine in definite proportions to one another by mass.