Peter Petrovich von Weymarn (commonly mis-spelt von Weimarn)[citation needed] (July 17, 1879 – June 2, 1935) was a chemist[1] known for his groundwork in colloid science.

He served as president of the Urals Metallurgical Institute in Ekaterinburg and was also associated with the Vladivostok Polytechnic University (1920–1922).

He then moved to Shanghai, where he worked at the Technical Center.

[1] In 1906 he stated the von Weymarn law: Colloidal dispersions are obtained from very dilute or very concentrated solutions but not from intermediate solutions.

The relative supersaturation ratio herein is defined by S=(Q-L)/L (where Q is the amount of the dissolved material and L is its solubility).