Consensual contracts are such as are founded upon and completed by the mere agreement of the contracting parties, without any external formality or symbolic act to fix the obligation . Real contracts are those in which it is necessary that there should be something more than mere consent, such as a loan of money, deposit or pledge, which, from their nature, require a delivery of the thing, (res.) Inst. 3, 14, 2; Id. 3. 15′; Halifax, Civil Law, b. 2, c. 15, No. 1. In the common law a contract respecting real property (such as a lease of land for years) is called a “real” contract. 3 Coke, 22a