It is a consequence of the rule that unsealed promises without consideration are not binding, that offers unless under seal or given for consideration may be revoked at any time prior to the creation of a contract by acceptance.41 Therefore, even though a definite time in which acceptance may be made, is named in such an offer, the offerer may, nevertheless, revoke his offer within that period.42 And even though the offer expressly states that it shall not be withdrawn, nevertheless, it may be.43 What communication amounts to a revocation is a question of construction. Any statement which dearly implies unwillingness to contract according to the terms of the offer is sufficient, though the word revoke is not used.44

40In Morse v. Bellows, 7 N. H. 549, 28 Am. Deo. 372, the offer requested the obtaining of a debtor's discharge from his creditors. Two years was held a reasonable time for this. On the other hand, in Smith v. Bruner, 68 111. App. 61, two years was held an unreasonable time for sinking a mining shaft.

41Dickinson v. Dodds, 2 Ch. Div. 463; Byrne v. Van Tienhoven, 5 C. P. Div. 344; Stevenson v. McLean, 5 Q. B. Div. 346; Moffett Ac Co. v. Rochester, 178 U. S. 373, 44 L. Ed. 1108; Borst v. Simpson, 90 Ala. 373; Timmons v. Bostwick, 141 Ga. 713, 82 S. E. 29; Crandall v. Willis, 166 111. 233, 46 N. E. 765; Miller v. Douville, 45 La. Amn. 214,12 So. 132; Lincoln v. Gay, 164 Mass. 537, 42 N. E. 95, 49 Am. St. Rep. 480; Brown v. Snider, 126 Mich. 198, 85 N. W. 570; Storch v. Duhnke, 76 Minn. 521, 79 N. W. 533; Winders v. Kenan, 161 N. E. 628, 77 S. E. 687; Outcault Advertising Co. v. Wilson, 186 Mo. App. 492, 172 S. W. 394; Brown v. Fanners' etc. Bank, 76 Or. 113, 147 Pac. 537; Herrin v. Scandinavian-American Bank, 65 Wash. 569, 118 Pac. 648; Brown Bros. Lumber Co. v. Preston Mill Co., 83 Wash. 648, 145 Pac. 964. And see cases in this section passim.

42 Bristol etc. Co. v. Magga, 44 Ch. Div. 616; Brown v. Savings Union, 134 Cal. 448, 66 Pac. 592; Cooper v. Lansing Wheel Co., 94 Mich. 272, 54 N. W. 39, 34 Am. St. Rep. 341; Davis v. Petty, 147 Mo. 374, 48 S. W. 944; Bosshardt Co. v. Crescent Oil Co., 171 Pa. 109, 32 Atl. 1120; Weaver v. Burr, 31 West Va. 736, 8 S. E. 743.

43Toledo Computing Scale Co. v. Stephens, 96 Ark. 606, 132 S. W. 926; Outcault Advertising Co. v. Young Hardware Co., 110 Ark. 123, 161 S. W. 142; Hargrove v. Crawford, 159 Ia. 522, 141 N. W. 423; Challenge Ac Mill Co. v. Kerr, 93 Mich. 328, 53 N. W. 555; Peck v. Freese, 101 Mich. 321, 59 N. W. 600; Cary v. Appo, 84 N. Y. S. 569; Howe Scale Co. v. Wolfs-baut, 170 N. Y. S. 943; National Refining Co. v. Miller, 1 S. Dak. 548, 553, 47 N. W. 962.

After an offer has been duly accepted, it is fundamental that revocation is no longer possible. Thus when parties have had a number of communications with one another by letter or otherwise regarding a proposed bargain, all should be considered, yet if once a definite offer has been made and it has been accepted without qualification, the complete contract thus arrived at cannot be affected by subsequent negotiations unless they amount to an agreement to modify or rescind the contract.45