What was the title of Albert Einstein's doctoral dissertation?

Albert Einstein’s doctoral dissertation was titled “A New Determination of Molecular Dimensions.” He completed the German original, “Eine neue Bestimmung der Moleküldimensionen,” in 1905 and submitted it to the University of Zurich.

The dissertation developed a way to estimate the size of molecules and Avogadro’s number by combining ideas from hydrodynamics and diffusion. Einstein examined how dissolved substances affect the viscosity of a liquid and used physical measurements of solutions to connect observable behavior with the properties of unseen molecules.

This title is easily confused with Einstein’s separate 1905 paper on Brownian motion. Brownian motion also dealt with molecular reality, but it was not the dissertation itself. Nor was the thesis titled “The Photoelectric Effect” or “On the Electrodynamics of Moving Bodies,” although those were among the other landmark works Einstein published during his annus mirabilis. The University of Zurich awarded him the doctorate in 1906.