All sales, conveyances, leases, or other dispositions of any lands or properties purchased, acquired, used, or dedicated in any manner by a city or town for municipal or other public purposes, purporting to have been made on behalf of the city or town for a valuable consideration prior to April 25, 1946, are hereby ratified, confirmed, and validated as of the date when made; provided, that this section shall not be construed to include any lands or properties acquired by gift or devise for the public use, whether or not the gift or devise is subject to a condition subsequent or reverter, or to property held by any city or town as part of a charitable trust.