The cemetery authority may set apart such portion as they see fit of the moneys received from the sale of the interment, entombment, or inurnment rights, in such cemetery or graveyard, which sums shall be kept separate from all other assets as an especial trust fund, and they shall keep the same invested in safe interest or income paying securities, for the purpose of keeping said cemetery or graveyard, and the interment, entombment, or inurnment rights therein, permanently in good order and repair, and the interest or income derived from such trust fund shall be applied only to that purpose, and shall not be diverted from such use.