Purchasers of the aforesaid lots shall receive a certificate of purchase from the sheriff, entitling the holder to a deed for the same, when payment in full shall be made according to law. If the purchaser of any lot fails to pay for the same within the time required by the county board, not to exceed one year in any case, the right of the purchaser to such lot shall be forfeited, and the same shall be again sold by the county board as hereinbefore provided.