(1)  Where the seller delivers to the buyer a quantity of goods less than he contracted to sell, the buyer may reject them, but it the buyer accepts the goods so delivered he shall pay for them at the contract rate.

   (2)  Where the seller delivers to the buyer a quantity of goods larger than he contracted to sell, the buyer may accept the goods included in the contract and reject the rest, or he may reject the whole. If the buyer accepts the whole of the goods so delivered, he shall pay for them at the contract rate.

   (3)  Where the seller delivers to the buyer the goods he contracted to sell mixed with goods of a different description not included in the contract, the buyer may accept the goods which are in accordance with the contract and reject the rest, or may reject the whole.

   (4)  The provisions of this section are subject to any usage of trade, special agreement or course of dealing between the parties.