The number of grams of an element equal numerically to the atomic
weight, as 16 grams of oxygen, 1 gram of hydrogen, 35.5 grams of
chlorine; all which might be expressed as gram-atoms of oxygen, hydrogen
and chlorine respectively.

The gram-atom approximately expresses the number of gram-calories
required to heat one gram of the substance 1º C. (1.8º F.). This is in
virtue of Dulong and Petit’s discovery that the atomic weight of an
element multiplied by its specific heat gives approximately a constant
for all elements.

[Transcriber's note: A gram-atom is the mass, in grams, of one mole of
atoms in a monatomic element. A mole consists of Avogadro's number of
atoms, approximately 6.02214E23.]