13. Every warehouseman shall keep in his warehouse the goods of one depositor separate from the goods of other depositors and from other goods, of the same depositor for which a separate receipt has been issued in such manner as to permit at all times the identification and easy delivery of goods deposited:
Provided that where standardized and graded goods are deposited in a warehouse, the same variety of goods belonging to the same or different depositors may, subject to any contrast to the contrary, be pooled together and each depositor shall be entitled only to his portion of the goods according to weight or quantity, as the case may be, as shown in his receipt, having due regard to driage or shrinkage.