Explanation:

Section-73

According to Section 73. Right to proceeds of revenue sale or compensation on acquisition.—(1)Where the mortgaged property or any part thereof or any interest therein is sold owing to failure to pay arrears of revenue or other charges of a public nature or rent due in respect of such property, and such failure did not arise from any default of the mortgagee, the mortgagee shall be entitled to claim payment of the mortgage-money, in whole or in part, out of any surplus of the sale-proceeds remaining after payment of the arrears and of all charges and deductions directed by law. 

Para 8 of Girdhar Lal And Anr. vs Alay Hasan Musanna AIR 1938 All 221 states that:
'The original section 73 of the TP Act was also based on the principle of substituted security.'