Chapter Four of the Paris Manuscript of the Institutions de Physique is now online, and can be found here.
One intriguing feature of the manuscript is that in version B, Du Châtelet includes a discussion of distinctively philosophical hypotheses, which she describes as one of the methods for discovering truth. At this stage, it is with respect to philosophy that she writes that hypotheses are often all that is within our capacity (a notre portée, 91v). However, in the next revision stage, the reference to philosophical hypotheses is removed. Here it is hard not to think of Christian Wolff’s presentation—recently discussed by Christian Leduc and Corey Dyck, among others—of some of his key metaphysical claims (such as pre-established harmony) as hypotheses that cannot be strictly proven.