Experimental determination of the Avogadro constant

Since the time Cannizzaro expounded a system of atomic weight determination in the Karlsruhe Congress in 1860 10], and firmly established Avogadro hypothesis, there have been dozens of experimental methods for determining the Avogadro number. Many of these methods seek to determine a fundamental physical constant such as charge of an electron or the Boltzmann constant whose value for one mole of particles is precisely known. Ingenious methods that have been devised for the measurement of these fundamental constants are discussed in this article.