§ 572. When the party to whom an offer or promise has been made makes no express promise in return, the contract is said to be unilateral; and it is not binding until accepted. Indeed, it cannot properly be called a contract before acceptance. Upon being accepted, the offerer or promisor becomes bound to perform his agreement. But as to the other, if any thing still be necessary on his part to enable the offerer to fulfil his engagement, he may, it seems, refuse to take the step without incurring liability.2 For instance, if a person offer to supply another with iron, he may, before acceptance retract his offer; but after acceptance he will be bound to supply the iron according to his offer, when it is ordered. And if it be not ordered, it is held that he has no right of action against the other party, notwithstanding the acceptance.3 The reason probably is, that the acceptance, considered as a promise, is without consideration.