We have recently analysed the inks in some of the folios of Vol. 72 of Manoscritti Galialeiani, kept at the Biblioteca Nazionale Centrale di Firenze, which contains a collection of loose handwritten sheets containing undated notes, data from experiments and propositions on the problems of motion from different periods of Galileo's life. This paper reports specific results obtained from the analysis of some of these propositions, which allowed to make a contribution to their chronological attribution and therefore to the solution of some historical controversies. Even in the case where the "e;absolute"e; chronological attributions colud not to be made on the basis of comparison with dated documents, the PIXE results provided useful information to deny or confirm the hypothesis that different propositions were written in the same or in different periods.