Mortgages of land may be made in substantially the following form: The mortgagor (here insert name or names) mortgages to (here insert name or names) to secure the payment of (here insert the nature and amount of indebtedness, showing when due, rate of interest, and whether evidenced by note, bond or other instrument or not) the following described real estate (here insert description) situated in the county of . . . . . ., state of Washington.
Dated this . . . . day of . . . . . ., (year) . . . .
Every such mortgage, when otherwise properly executed, shall be deemed and held a good and sufficient conveyance and mortgage to secure the payment of the money therein specified. The parties may insert in such mortgage any lawful agreement or condition.