3. The retraction may be express, as when notice is given that the offer is withdrawn; or, tacit as by the death of the offering party, or his inability to complete the contract; for then the consent of one of the parties has been destroyed, before the other has acquired any existence; there can therefore be no agreement. 16 Toull. 55.
4. After pleading guilty, a defendant will, in certain cases where he has entered that plea by mistake or in consequence of some error, be allowed to retract it. But where a prisoner pleaded guilty to a charge of larceny, and sentence has been passed upon him, he will not be allowed to retract his plea, and plead not guilty. 9 C. & P. 346; S. C. 38 E. C. L. R. 146; Dig. 12, 4, 5.