15. Every warehouse-man in the absence of any reasonable or lawful excuse shall without unnecessary delay deliver the agricultural produce stored in his warehouse to the depositor on a demand made by him and on surrender of the warehouse receipt duly discharged and on payment of the charges due to the warehouse-man. Subject to any agreement between the warehouse-man and the depositor, the latter may take partial delivery of his agricultural produce stored in the warehouse: Provided that the loss of weight by evaporation of moisture and shrinkage of its gain by absorption of moisture shall be accounted for when agricultural produce is delivered wholly or in part under the provisions of this section or when disposed of as provided in section 14.