​A new agreement will only act as a novation between the parties. Changing to another contract of sale that has different subject or object than the previous one.

Article 1460. A thing is determinate when it is particularly designated or physical segregated from all others of the same class. The requisite that a thing be determinate is satisfied if at the time the contract is entered into, the thing is capable of being made determinate without the necessity of a new or further agreement between the parties. ​

​Article 1461. Things having a potential existence may be the object of the contract of sale.

The efficacy of the sale of a mere hope or expectancy is deemed subject to the condition that the thing will come into existence.

The sale of a vain hope or expectancy is void. (n)

​Article 1462. The goods which form the subject of a contract of sale may be either existing goods, owned or possessed by the seller, or goods to be manufactured, raised, or acquired by the seller after the perfection of the contract of sale, in this Title called "future goods."

There may be a contract of sale of goods, whose acquisition by the seller depends upon a contingency which may or may not happen.

​Article 1465. Things subject to a resolutory condition may be the object of the contract of sale.

​Article1466. In construing a contract containing provisions characteristic of both the contract of sale and of the contract of agency to sell, the essential clauses of the whole instrument shall be considered.

​Article1468. If the consideration of the contract consists partly in money, and partly in another thing, the transaction shall be characterized by the manifest intention of the parties. If such intention does not clearly appear, it shall be considered a barter if the value of the thing given as a part of the consideration exceeds the amount of the money or its equivalent; otherwise, it is a sale.

​Article1470. Gross inadequacy of price does not affect a contract of sale, except as it may indicate a defect in the consent, or that the parties really intended a donation or some other act or contract

​Article 1471. If the price is simulated, the sale is void, but the act may be shown to have been in reality a donation, or some other act or contract.