This section is from the book "The Law Of Contracts", by Theophilus Parsons. Also available from Amazon: The law of contracts.
It sometimes happens that a consideration is void in part; and the question arises whether this fact makes the whole consideration invalid, and the promise itself of no obligation. If one or more of several considerations, which are recited as the ground of a promise, be only frivolous and insufficient, but not illegal, and others are good and sufficient, then undoubtedly the consideration may be severed, and those which are void disregarded, while those which are valid will sustain the promise. (m) But where the consideration is entire and incapable of severance, then it must be wholly good or wholly bad. If the promise be entire and not in writing, and a part of it relate to a matter which by the statute of fraud should be promised in writing, such part being void, avoids the whole contract, (n) but if it be * such in its nature that it may be divided, and the part not required to be in writing by the statute may be enforced without injustice to the promisor, that portion of the agreement will be binding. (0)
(kk) New York, etc. Co. v. De Wolf, 31 N. Y. 273.
(kl) Westminster College v. Gamble, 42 Mo. 411.
(km) Ball v. Dunsterville, 4 T .R. 313; Cooch v. Goodman, 2 Q. B. 580, 598.
(l) Williams College v. Danforth, 12 Pick. 541.
(m) Parish v. Stone, 14 Pick. 198; King v. Sears, 2 C. M. & R. 48; Jones v.
Waite, 5 Bing. N. C. 341; Sheerman v. Thompson, 11 A. & E. 1027; Best v. Jolly, 1 Sid. 38; Cripps v. Golding, 1 Roll. Abr. 30, Action sur Case, pl. 2; Bradburne v. Bradburne, Cro. E. 149 , Coulston v. Carr, id. 848; Crisp v. Gamel, Cro. J. 127; Shackell v. Rosier, 2 Bing. N. C. 646, per Tindal, C. J.; Erie Railway v. Union, etc. Co. 35 N. J. L. 240.
(n) Mechelen v. Wallace, 7 A. & E. 49;
1 As to whether the obligation of subscribers to a subscription paper is joint or several, see Davis v. Shafer, 50 Fed. Rep. 764; Darnall v. Lyon, 19 Southwestern Rep. 506 (Tex. App).
 
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