(1)  Except as otherwise hereinafter provided in this section, the court shall not direct the specific performance of a part of a contract.

   (2)  Where a party to a contract is unable to perform the whole of his part of it, but the part which must be left unperformed be a only a small proportion to the whole in value and admits of compensation in money, the court may, at the suit of either party, direct the specific performance of so much of the contract as can be performed, and award compensation in money for the deficiency.

   (3)  Where a party to a contract is unable to perform the whole of his part of it, and the part which must be left unperformed either--

   (a)  forms a considerable part of the whole, though admitting of compensation in money; or

   (b)  does not admit of compensation in money;

he is not entitled to obtain a decree for specific performance; but the court may, at the suit of the other party, direct the party in default to perform specifically so much of his part of the contract as he can perform, if the other party--

   (i)  in a case falling under clause (a), [pays or has paid] the agreed consideration for the whole of the contract reduced by the consideration for the part which must be left unperformed and in a case falling under clause (b) ¹pays or has paid the consideration for the whole of the contract without any abatement; and

   (ii)  in either case, relinquishes all claims to the performance of the remaining part of the contract and all right to compensation, either for the deficiency or for the loss or damage sustained by him through the default of the defendant.

   (4)  When a part of a contract which, taken by itself, can and ought to be specifically performed, stands on a separate and independent footing from another part of the same contract which cannot or ought not to be specifically performed the court may direct specific performance of the former part.

   Explanation.--For the purposes of this section, a party to a contract shall be deemed to be unable to perform the whole of his part of it if a portion of its subject-matter existing at the date of the contract has ceased to exist at the time of its performance.