Because Avogadro's number is linked to a number of other physical constants, its value can be used to express other units, such as the kilogram.

Chemists use Avogadros number to determine how many molecules are in a volume. Phil Plait, an astronomer and blogger for Slate, explains: ...

However, I am afraid that the use of Avogadro's name in this connexion led me to overlook Loschmidt's work, so that I was content to find and verify a short reference to Maxwell.