That so much of the lands granted to the state of Michigan by acts of congress of June 3, 1856, and March 4, 1879, upon the route from Grand Haven to Flint and thence to Port Huron, extending from Grand Haven to Flint as in said acts designated, as have been purchased in good faith from Augustus D. Griswold or his grantees previous to the nineteenth day of January, 1876, William R. Bowes, as trustee of the Port Huron and Lake Michigan railroad company, or his successor, or of Amos Gould, or of either of their grantees, previous to the twenty-ninth day of January, A.D. 1881, shall have patents issued to them respectively for such lands: Provided, That the same shall be in 1 body and not in detached parcels, and shall not exceed 160 acres: And provided further, That such claimant or his grantors shall have been in actual and continued possession of such lands, and shall have resided thereon since January 1, 1881, and shall have made valuable improvements thereon: And provided further, That any number of acres received by such person or his grantors by virtue of Act No. 275 of the legislature of the state of Michigan of 1881, approved June eleventh, 1881, shall be deducted from the number of acres to be received by virtue of this section.