[1] A simple statement of the law is:[2] The acceptance of the law allowed tables of element equivalent weights to be drawn up.
These equivalent weights were widely used by chemists in the 19th century.
The law states that if two different elements combine separately with a fixed mass of a third element, the ratio of the masses in which they combine are either the same or are in simple multiple ratio of the masses in which they combine with each other .
The law of reciprocal proportions was proposed in essence by Richter,[1] following his determination of neutralisation ratios of metals with acids.
In the early 19th century it was investigated by Berzelius, who formulated it as follows:[3] Later Jean Stas showed that within experimental error the stoichiometric laws were correct.