Iowa Code § 589.22: Certain loans, contracts, and mortgages.

All loans, contracts, and mortgages which are affected by the repeal of 1898 Iowa Acts, ch. 48, are hereby legalized so far as to permit recovery to be had thereon for interest at the rate of eight percent per annum, but at no greater rate, and nothing contained in such contracts shall be construed to be usurious so as to work a forfeiture of any penalty to the school fund.