Mitscherlich's law of isomorphism, or the law of isomorphism, is an approximate law suggesting that crystals composed of the same number of similar elements tend to demonstrate isomorphism.
Mitscherlich's law is named for German chemist Eilhard Mitscherlich, who formulated the law and published it between 1819 and 1823.
According to Ferenc Szabadváry, one of the clues that helped Berzelius determine the atomic weights of the elements was "the discovery of Mitscherlich that compounds which contain the same number of atoms and have similar structures, exhibit similar crystal forms (isomorphism)."