Absolute Value of Avogadro's Number and the Soundness of Crystals

Abstract

The experimental determination of Avogadro's number by the x-ray-density method is uncertain because of imperfections in crystals. It is proposed to regard the lattice of purest calcite as a reference lattice because of its proximity to a sound lattice, and to accept the value ${N}_{0}=6.02567\ifmmode\times\else\texttimes\fi{}{10}^{23}$ g ${\mathrm{mole}}^{\ensuremath{-}1}$ (phys.) which is equivalent to 6.02403\ifmmode\times\else\texttimes\fi{}${10}^{23}$ g ${\mathrm{mole}}^{\ensuremath{-}1}$ (chem.) for Avogadro's number as derived from measurements on pure calcite. The perfection of the lattices of all other crystalline substances then would be determined in comparison with the calcite as either sound (equal in perfection to that of calcite) within the error limits or as defective (vacancies, interstitial atoms), using the number above for the calculations.