But what are these 'methods of the empirical sciences' ? And what do we call 'empirical science' ? Now it is far from obvious, from a logical point of view, that we are justified in inferring ...

Iansiti, Marco, and Jonathan West. "From Physics to Function: An Empirical Study of R&D in the Semiconductor Industry." Harvard Business School Working Paper, No. 97-073, June 1997.

You can work out the molecular formula from the empirical formula, if you know the relative mass formula (M r) of the compound. Add up the atomic masses of the atoms in the empirical formula.