When a thing has been formed by the admixture of several materials of different owners, and neither can be considered the principal substance, an owner without whose consent the admixture was made may require a separation, if the materials can be separated without inconvenience. If they cannot be thus separated, the owners acquire the thing in common, in proportion to the quantity, quality, and value of their materials; but if the materials of one were far superior to those of the others, both in quantity and value, he may claim the thing on reimbursing to the others the value of their materials.