There may be a sale of an undivided share of a specific mass of fungible goods though the seller purports to sell and the buyer purports to buy a definite number, weight or measure of the goods in the mass, and though the number, weight or measure of the goods in the mass is undetermined. Which of the following rules is correct? I. If the quantity, number, weight or measure, of the mass is more than the quantity sold, the parties shall become co-owners of the mass. II. If the quantity of the mass is less than the quantity sold, the buyer becomes the owner of the whole mass, with the seller being bound to make good the deficiency from goods of the same kind and quality, unless a contrary intent appears.