Said appraisers shall appraise all lots, pieces or parcels of land, unclaimed or not conveyed by virtue of any law, in such town, at their just and full cash value, and file their written appraisement thereof with said clerk. Said appraisement shall contain a description of each lot, piece or parcel of land so appraised, and a statement of the cash value of the same. Said appraiser shall make a separate statement of the value of such lots, pieces and parcels of land without improvements, and the value of such improvements, and the aggregate value of both. There shall be attached to such appraisement a written affidavit of said appraisers verifying each statement of such appraisement and alleging that each of such lots and parcels of land is appraised at its just and full value. This appraisement shall be required only in cases where the time has expired by law for claimants to file their statements.