2. In order to make a contract, it is essential there should be an agreement; a bare communication or conference will not, therefore, amount to a contract; nor can evidence of such communication be received in order to take from, contradict, or alter a written agreement. 1 Dall. 426; 4 Dall. 340; 3 Serg. & Rawle, 609. Vide Pour-parler; Wbarton's Dig. Evid. R.