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.
If the consideration appears in the written contract as a contractual term thereof, an oral agreement whereby an additional or other consideration is provided for violates the parol evidence rule and is unenforceable.1 The fact that the consideration is set forth as a contractual term implies that no other consideration exists.2 Thus in a contract for the sale of land, if it specifies the amount which the vendee agrees to pay, an oral contract whereby he agrees to pay more is unenforceable.3 If a deed provides that the grantee assumes and agrees to pay a mortgage, the effect of such covenant can not be varied by evidence tending to show the actual consideration for the deed,4 A contract which requires two persons to execute a mortgage as consideration precludes extrinsic evidence tending to show that one of such parties was not to be liable personally.5 So in other contracts of sale, where the amount to be paid is agreed upon as a contractual term, oral contracts for the assumption of the vendor's debts in addition to the amounts specified in the contract, are unenforceable.6 So where A agreed to sell B quinine at fifty-nine cents an ounce, an oral agreement whereby A agreed to advance the price to sixty-one cents per ounce, and to send out trade circulars announcing such advance, is unenforceable.7 Under a written agreement to pay an additional price for property upon the extension of an option on such property for a year, extrinsic evidence is inadmissible to show that a corresponding increase was to be made in each successive year, in consideration of an additional extension of time.8 Where an injured employe signs a release of damages in consideration of payment to him of twenty-five dollars and all the expenses of physicians and hospital, an oral agreement that the twenty-five dollars was a mere gratuity, and that, accordingly, the only consideration was the payment of the expenses for physicians and hospital, is unenforceable.9 So in an agreement for the sale of stock at a certain price per share, an oral agreement that the vendee should pay only one-fourth of the amount set forth in the written contract is unenforceable.10 So where a bill of sale sets forth the price to be paid for stock, an oral contract to furnish such certificates and proofs of pedigree of such stock as would enable the vendee to have them registered is unenforceable.11 So where a written contract shows that the consideration was to be determined in the future according to the amount of work done, but was "not to exceed five hundred dollars per week," an oral contract fixing the amount of compensation is unenforceable.12 Under a contract by which A agreed to employ B as superintendent of a building in payment of B's securing a loan for A, extrinsic evidence is inadmissible to show that A had also agreed to pay a commission to B for securing such loan.13 So where a contract and conveyance of a right of way shows the consideration, an oral contract for an under-crossing, as an additional consideration, is unenforceable.14 If a note shows oh its face that it is given in consideration of the location of a railroad at a certain point, extrinsic evidence is inadmissible to show that the payee had also agreed to build a station at a certain point.15 Tinder a written contract which releases damages for the location of a railway crossing, in consideration of the payment of a specified sum of money, extrinsic evidence is inadmissible to show that in addition to the consideration recited in such contract, the railway company had agreed to restore a certain stream of water to its original condition.16 And so where A sold certain patents to B, and guaranteed their validity, and B was to pay A certain royalties thereon, a subsequent written contract whereby, in lieu of such royalties, A is to receive a lump sum, can not be shown to rest in part upon an oral contract whereby B releases A from his contract, guaranteeing the validity of such patents.17 So oral evidence can not be considered to show a lower rent than that specified in a lease.18 If the lessee covenants to construct and maintain a factory upon the leased premises, extrinsic evidence is inadmissible to show that such covenant was not intended as a part of the consideration for the lease.19 A contract by which A agrees to subscribe to certain stock in a corporation, and B agrees to convey a certain building to such corporation, can not be varied by evidence that B had agreed to expend a specified amount in remodeling such building.20 A contract for the dissolution of a partnership which specifies the amount of liability which each partner is to assume, can not be varied by evidence of an oral agreement.21 If a lease contains a provision giving an option to the lessee and it appears that such option is a part of the consideration for the lessee's covenant to pay rent, extrinsic evidence is inadmissible to show that such option was inserted after the other terms of the lease had been agreed upon and that accordingly such option was without consideration.22
22 Elliott Contracting Co. v. Portland, 88 Or. 150, 171 Pac. 760.
1 United States. Watkins Salt Co. v. Mulkey, 226 Fed. 739, 141 C. C. A. 11.
Arkansas. Jones v. Epstein, - Ark. - , 204 S. W. 217.
California. Cameror v. Ayres, 175 Cal. 662, 166 Pac. 801; Harding v. Robinson, 175 Cal. 534, 166 Pac. 808.
Georgia. Brosseau v. Jacobs' Pharmacy Co., 147 Ga. 185, 93 S. E. 293.
Illinois. Schneider v. Turner, 130 111. 28, 6 L. R. A. 164.
Indiana. Indianapolis Union Ry. v. Houlihan, 157 Ind. 494, 60 N. E. 943.
Iowa. Larson v. Smith, 174 Ia. 619, 156 N. W. 813.
Kentucky. Paris v. Lilleston (Ky.), 60 S. W. 919.
Maryland. Cassard v. McGlannan, 88 Md. 168, 40 Atl. 711.
Minnesota. Kramer v. Gardner, 104 Minn. 370, 22 L. R. A. (N.S.) 492, 116 N. W. 925.
North Carolina. Grier v. Ins. Co., 132 N. Car. 542, 44 S. E. 28; Woodson v. Beck, 151 N. Car. 144, 31 L. R. A. (N.S.) 235, 65 S. E. 751.
Oregon. Muir v. Morris, 80 Or. 378. 157 Pac. 785 [denying rehearing, Muir v. Morris, 80 Or. 378, 154 Pac. 117].
South Dakota. Emerson-Branting-ham Implement Co. v. Edgar, 39 S. D. 139, 163 N. W. 575; Roaholt v. Woulpli, - S. D. - -, 167 N. W. 158.
Texas. Kahn v. Eahn, 94 Tex. 114, 58 S. W. 825.
Washington. Eggleston v. Pantages, 93 Wash. 221, 160 Pac. 425; Kelley v. Smith, 101 Wash. 475, 172 Pac. 542.
West Virginia. Buena Vista Co. v. Billmyer, 48 W. Va. 382, 37 S. E. 583.
2 Muir v. Morris, 80 Or. 378, 157 Pac. 785 [denying rehearing, Muir v. Morris, 80 Or. 378, 154 Pac. 117].
3 Trice v. Yeoman, 60 Kan. 742, 57 Pac. 955.
4 Lamoille County Savings Bank & Trust Co. v. Belden, 90 Vt. 535, 98 Atl. 1002.
5Rhodes v. Owens, 101 Wash. 324, 172 Pac. 241.
6 Thompson v. Bryant, 75 Miss. 12, 21 So. 655; Walter v. Dearing (Tex. Civ. App.), 65 8. W. 380.
7Engelhorn v. Reitlinger, 122 N. Y. 76, 9 L. R. A. 548, 25 N. E. 297.
8 Samuelson v. Palmer, 96 Kan. 587, 152 Pac. 627.
9 Indianapolis Union R. R. v. Houlihan, 157 Ind. 494, 54 L. R. A. 787, 60 N. E. 943.
10 Libby v. Spring & Land Co., 67 N. H. 587, 32 Atl. 772.
11 McFarland v. McGill, 16 Tex. Civ. App. 298, 41 S. W. 402 [citing, Pickett v. Green, 120 Ind. 584; Pennsylvania Co. v. Dolan, 6 Ind. App. 109].
12 United Press v. Press Co., 164 N. Y. 406, 53 L. R. A. 288, 58 N. E. 527.
13 Cameron v. Ayree, 175 Cal. 662, 166 Pac. 801.
14Schrimper v. Ry. (Ia.), 82 N. W. 016.
15Rosholt v. Woulph, - S. D. - , 107 N. W. 158.
16 Evans v. Northern Pacific Ry., 117 Minn. 4, 134 N. W. 294.
17 Sandage v. Mfg. Co., 142 Ind. 148, 51 Am. St. Rep. 165, 34 L. R. A. 363, 41 N. E. 380.
18 Merchants' State Bank v. Ruet-tell, 12 N. D. 519, 97 N. W. 853.
19 Jones v. Epstein, - Ark. - , 204 S. W. 217.
20Egg1eston v. Pantages, 93 Wash. 221, 160 Pac. 425.
21 Muir v. Morris, 80 Or. 378, 157 Pac. 785 [denying rehearing, Muir v. Morris, 80 Or. 378, 154 Pac. 117].
22 Larson v. Smith, 174 Ia. 619, 156 N. W. 813.
If A gives a due bill for a premium upon a life insurance policy, extrinsic evidence is inadmissible to show that the amount which A agrees to pay was not to be paid, but that he was to pay a smaller amount and surrender another policy.23