Under the hypotheses of Proposition 9, let M be an A-module. We write fβα=iMSβ,Sα for α≤β,fα=iMS,Sα for all α∈I and let fα′ be the canonical mapping from Sα−1M to lim→Sα−1M; then there exists an S−1A-isomorphism g of S−1M onto lim→Sα−1M such that g∘fα=fα′ for all a∈I.
The corollary follows immediately from the definitions Sα−1M=M⊗ASα−1A and S−1M=M⊗AS−1A and the fact that taking direct limits commutes with tensor products (Algebra, Chapter 11, § 6, no. 3, Proposition 7).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.