The proposition that a prior contract may be modified or rescinded by a subsequent contract, implies that such subsequent contract must have the elements necessary to the formation of a valid original contract. The new contract requires the assent of all the parties to the original contract or of their successors, in interest to operate as a discharge thereof.1 One of the parties to a contract can not modify such contract or terminate it lawfully unless the other party assents thereto.2 A contract between A and B can not be modified by A's declaration of his wish to avoid the contract and the promise of B's agent to try to induce B to consent thereto.3 So a contract between A and B can not be abrogated or modified by a subsequent contract between B and C, to which A does not assent.4 An agreement between A and B, to divide the profits to be received from the sale of certain lands, can not be modified by an agreement between B and C, whereby C agrees that B shall have any bonus which may be paid upon a particular transaction with respect to certain lands included in the contract between A and B.5 If a contract is made by which B is to act as factor for A, and such contract makes no provision with reference to insurance, the principal can not add to such contract a provision requiring the factor to keep the goods insured,6 as by inserting in the invoices a provision that goods were to be kept covered by insurance for the benefit of the consignor.7 If A and B have entered into a building contract, such contract is not terminated by A's offer to pay a certain sum for a building to be constructed according to a new plan which A submitted to B, but to which B never agreed.8 A notice by an engineer of the United States to a contractor, to the effect that a greater quantity of material would probably be required than was provided for by the contract, is not such a contract for such additional amount of material that the contractor can recover probable profits for furnishing such material in case such material is not in fact needed for the performance of the contract.9 So a promise by a construction company to pay the salary of the president of a railway company, will not discharge the railway company from liability to its president unless the latter assents to such new contract.10

1 United States, Utley v. Donaldson, 94 U. S. 29, 24 L. ed. 54; Smoot v. United States, 237 U. S. 38. 59 L. ed 829 [affirming judgment, Smoot v. United States, 48 Ct. Cl. 4271; Frank-furt-Barnett Co. v. Prym Co., 237 Fed. 21, L. R. A. 1918A, 602; In re Mullings Clothing Co., 238 Fed. 58, L. R. A. 1918A, 539.

Alabama. Pittsburgh Reliance Life Ins. Co. v. Garth, 192 Ala. 91, 68 S. W. 871.

Colorado. Adams v. Guiraud, 62 Colo. 114, 169 Pac. 580.

Connecticut. Smith v. Miller. 79 Conn. 624, 66 Atl. 172; Trowbridge v. Jefferson Auto Co., 92 Conn. 569, 103 Atl. 843.

District of Columbia. Fontano v. Robbing, 22 D. C. App. 253.

Georgia. Central of Georgia, Ry. Co. v. Gortatowsky, 123 Ga. 366, 51 S. E. 469; Bearden Mercantile Co. v. Madison Oil Co., 128 Ga. 695, 58 S. E. 200; Bailey State Bank v. Heinse, 178 Ia. 1203, 160 N. W. 903.

Maryland. B. F. Sturtevant Co. v. Cumberland, 106 Md. 587, 68 Atl. 351.

Massachusetts. Picard v. Beers, 195 Mass. 419, 81 N. E. 246; Boyden v. Hill, 198 Mass. 477, 85 N. E. 413.

Minnesota. Northwestern Fire & Marine Ins. Co. v. Connecticut Fire Ins. Co., 105 Minn. 483, 117 N. W. 825.

Nebraska. Herpolsheimer v. Christopher, 76 Neb. 352, 107 N. W. 382.

New Jersey. Sperry & Hutchinson Co. v. Hertzberg, 69 N. J. Eq. 264, 60 Atl. 368; Ferber v. Cona, 91 N. J. L. 688, 103 Atl. 471.

North Carolina. Brown v. Lumber Co., 117 N. Car. 287, 23 S. E. 253; Billings v. Wilby, 175 N. Car. 571, 90 S. E. 50.

North Dakota. Libby v. Barry, 15 N. D. 286, 107 N. W. 972; Bellaire Stove Co. v. Midland Steel Co., 66 O. S. 1, 63 N. E. 587.

Wisconsin. Dickinson v. Plow Co., 101 Wis. 157. 76 N. W. 1108.

2 United States. Central Coal & Coke Co. v. Good, 120 Fed. 793.

Colorado. Adams v. Guiraud, 62 Colo. 114, 169 Pac. 580.

Connecticut. Trowbridge v. Jefferson Auto Co., 92 Conn. 569, 103 Atl. S43.

District of Colombia. Fontano v. Robbins, 22 D. C. App. 253.

Georgia. Oklahoma Vinegar Co. v. Carter, 116 Ga. 140, 94 Am. St. Rep. 112, 59 L. R. A. 122, 42 S. E. 378; Central of Georgia, Ry. Co. v. Gor-tatowsky, 123 Ga. 366, 51 S. E. 469.

Maryland. B. F. Sturtevant Co. v. Cumberland, 106 Md. 587, 68 Atl. 351.

Massachusetts. Picard v. Beers. 195 Mass. 419, 81 N. E. 246.

New Jersey. Sperry & Hutchinson Co. v. Hertzberg, 69 N. J. Eq. 264, 60 Atl. 368.

Ohio. Bellaire Stove Co. v. Midland Steel Co., 66 O. S. 1, 63 N. E. 587.

Wisconsin. Dickinson v. Plow Co., 101 Wis. 157, 70 N. W. 1108.

3McCormick Harvesting Machine Co. v. Markert, 107 Ia. 340, 78 N. W. 33.

4 Currier v. Kretzinger, 162 111. 511, 44 X. E. 882; McKay v. Myers. 168 Mass. 312, 47 N. E. 98; Ludlow v. Strong, 53 N. J. Eq. 326, 31 Atl. 409; Bowen v. Ry., 34 S. Car. 217, 13 S. E. 421.

5 Currier v. Kretzinger, l62 IR. 511, 44 N. E. 882.

To abrogate11 or modify12 a prior contract, it is necessary that the minds of the parties to the original contract should meet by offer and acceptance upon the terms of the new contract. Mere negotiations, consisting of unaccepted offers, can not affect a prior contract.13 Subsequently, conversations as to the meaning of a prior contract, not amounting to a new contract and not giving rise to an estoppel, are not intended to change the legal effect of such contract, and hence do not operate as such change.14 In order to establish a subsequent oral modification of an oral written contract, it must be shown that the minds of the parties meet upon such subsequent modification.15 An ambiguous statement which is not accepted as an offer by the adversary party, can not operate to modify a prior contract.16 Mere statements by one party to a contract, made after the contract is entered into, can not modify or abrogate it if not assented to by the adversary party.17 A subsequent conversation between the parties to a written contract had immediately after signing it, whereby they discuss and construe it, does not of itself affect the contract, since the parties had no intention of modifying it by such conversation.18 Notice by one party to a contract of a change desired or insisted on by him, does not amount to a modification unless the adversary party assents thereto either expressly or impliedly. Thus a notice by an employer to an employe, with whom he has an unexpired contract, of a reduction in the contract rate, is without effect if the employe does not assent thereto.19 A bill of lading sent to a consignee after an oral agreement for shipping goods has been entered into between himself and the carrier, can not limit the carrier's liability.20 An oral contract can not be modified by a written memorandum signed by one person and setting forth terms different from those of the original contract.21 A contract for the sale of goods can not be changed to a consignment or agency for sale by a provision in an invoice subsequently forwarded to the purchaser, even though he does not actively dissent therefrom.22 A sold an elevator to B, who bought for C. Subsequently B wrote to A that he did not expect to be called to pay for the elevator until C paid B. A did not dissent and thereafter put the elevator in place. It was held that A's silence did not amount to an acceptance of B's request, even if the elevator was put in after the time fixed by the original contract.23 General authority by some promoters of a corporation to others, to do whatever the latter think best, abrogates a prior contract that they would retain a controlling interest in the stock of such corporation and not sell their shares without first offering them to their associates where, in order to secure the co-operation of others, without which such corporation could not be organized, it is necessary to let them have a controlling interest in such corporation.11