How and When Did Avogadro's Name Become Associated with Avogadro's Number?

The history behind the association of Avogadro's name related to the hypothesis that equal volumes of gases at constant temperature and pressure contain equal numbers of molecules is explored. The findings suggest that the index entry "Avogadro's Number" did not become common in American college texts until the 1930s and was rare in American high school texts before the 1950s.