A domestic fire insurance company may not declare any dividend except from the surplus profits arising from its business. In estimating the surplus profits, there must be reserved as unearned premiums a sum equal to forty percent of the amount of premiums on all unexpired risks and policies, and there also must be reserved all sums due the company on bonds, mortgages, stocks, and book accounts upon which no part of the principal or accrued interest has been paid during the year preceding the estimate of the profits and upon which suit for foreclosure or collection has been commenced, or a judgment upon which has remained unsatisfied for more than one year.