Section 58. Alternative promise, one branch being illegal

58. Alternative promise, one branch being illegal .—In the case of an alternative promise, one branch of which is legal and the other illegal, the legal branch alone can be enforced. Illustration A and B agree that A shall pay B 1,000 rupees, for which B shall afterwards deliver to A either rice or smuggled opium. This is a valid contract to deliver rice, and a void agreement as to the opium. Appropriation of payments 59.Application of payment where debt to be discharged is indicated .—Where a debtor, owing several distinct debts to one person, makes a payment to him, either with express intimation, or under circumstances implying, that the payment is to be applied to the discharge of some particular debt, the payment, if accepted, must be applied accordingly.