“ In our opinion, the contention cannot be sustained. The plaintiff's rights arising out of his contract were in no wise impaired by the statute of 1907. It did not interpose any obstacle to their assertion by him, and neither did it leave him without a suitable remedy for their ascertainment and enforcement. If the attempted forfeiture was invalid before, it continued to be so thereafter. ”

“ The statute (Laws [Kan.] 1879, chap. 161, § 2) prescribing the mode of forfeiture in force since before the plaintiff's contract was made, reads as follows:
'If any purchaser of school land shall fail to pay the annual interest when the same becomes due, or the balance of the purchase money when the same becomes due, it shall be the duty of the county clerk of the county in which such land is situated, immediately to issue to the purchaser a notice in writing, notifying such purchaser of such default ”

“ The notice above provided for shall be served by the sheriff of the county by delivering a copy thereof to such purchaser, if found in the county, also to all persons in possession of such land; and if such purchaser cannot be found, and no person is in possession of said land, then by posting the same up in a conspicuous place in the office of the county clerk. ”