The donor and done may agree that on the happening of any specified event which does not depend on the will of the donor a it shall be suspended or revoked; but a gift which the parties agree shall be revocable wholly or in part at the mere well of the donor is void wholly or in part, as the case may be.

   A gift also be revoked in any of the cases (save want or failure of consideration) in which, if it were a contract, it might be rescinded.

   Save as aforesaid, a gift cannot be revoked.

   Nothing contained in this section shall be deemed to affect the rights of transferees for consideration without notice.

Illustration.

   (a)  a gives a field to B, reserving to himself, with B's assent, the right to take back the field in case B and his descendants dies before A, B dies without descendants in A's lifetime. A may take back the field.

   (b)  A gives a lakh of rupees to B, reserving to himself, with B's assent, the right to take back at pleasure Rs. 10, 000 out of the lakh. The gift holds good as to Rs. 90, 000, but is void as to Rs.10, 000, which continue to belong to A.