§12. The rule that a consideration is necessary to a valid contract applies to all contracts and engagements not under seal, except bills of exchange and negotiable notes after they have passed into the hands of an innocent indorsee. (See Promissory Notes.) In contracts under seal, a consideration is necessarily _implied_ in the solemnity of the instrument. §13. It is declared by the English statute of frauds, which prevails generally in the United States, that an agreement which is not to be performed within one year from the time of making it, shall not be valid, unless such agreement, or some memorandum or note thereof, is in writing, and signed by the party to be charged. The statutes of some of the states have adopted this provision of the English statute, and require further, that a special promise to answer for the debt, default, or misdoing of another person, and an agreement or promise upon consideration of marriage, (except mutual promises to marry,) shall likewise be void without such writing, in which the consideration shall be expressed. Chapter LV. Contracts of Sale. §1. A Sale is a transfer of the title to property to another person for a certain price; or the exchange of a commodity for its equivalent value in money. The exchange of one commodity for another, is _barter_. Unless the absolute title is conveyed, the contract is merely a mortgage. The same general principles of law which apply to contracts in general, are applicable to contracts of sale, viz.: the competency of the parties to contract; the sufficiency of the consideration; its legality and morality; the assent of the parties; and the absence of fraud. §2. To make a sale valid, the thing to be sold must have an _actual or a possible existence_, and be _capable of delivery_. Thus, if A sells a horse or certain goods to B; and if, at the time of the sale, the horse is dead, or the good? are destroyed; the sale is void. If the goods are partially destroyed, the buyer may either take them at a proportionate reduction of the price, or abandon the contract. §3. But, although the thing to be sold has no actual and present existence; yet if its future existence is possible, and if it is the product or increase of something to which the seller has a present right, it is the subject of sale. Thus, a man may sell the wool that may grow on his sheep, the fruit that may grow on his trees, or the future increase of his cattle. But he cannot sell the products of the sheep or cattle which he may hereafter buy. A man may, however, agree to procure goods which he has not, and to furnish at a future time, for a certain price; and his contract will be good; though this is not strictly a sale, but an agreement to sell.