This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
As has already been stated, a prior valid contract cannot be abrogated or modified by an alleged new contract unless both parties assent thereto.1 If one party manifests his intention in unequivocal language not to perform the contract unless modifled, this may amount to a breach,2 but it cannot relieve him from liability under his contract. If one person gives notice that he will not perform at all,3 or that he will not perform unless new terms which he specifies are made part of the contract,4 such conduct is a breach, but does not operate as a new contract. Thus if A has agreed to construct an ice-plant and refuses to complete it unless the adversary party will waive a claim for damages, such refusal is a breach.5
4 Pinchback v. Mining Co., 117 N. C. 484; 23 S. E. 425.
5 Lee v. Association, 97 Va. 160; 33 S. E. 556.
6 Kilgore v. Educational Society, 90 Tex. 139; 37 S. W. 598.
7 Lundahl v. Hansen. 147 111. 504; 35 N. E. 741; Emack v. Hughes, 74 Vt. 382; 52 Atl. 1061.
8 Bell v. Maximos, 85 Tex. 140; 19 S. W. 1070.
9 Lundahl v. Hansen, 147 111. 504; 35 N. E. 741.
10 Bernstein v. Meech, 130 N. Y. 354; 29 N. E. 255.
11 Gunther v. Gunther, 181 Mass. 217; 63 N. E. 402.
1 See Ch. LXII.