1153. Consideration by way of periodical payments.

Where the consideration for a conveyance on sale, or any part of it, consists of money payable periodically for a definite period not exceeding 20 years, so that the total amount payable can be previously ascertained, ad valorem stamp duty is charged on the total amount1. Where the periodical payments are to extend for a definite period exceeding 20 years or in perpetuity, or for an indefinite period not terminable with life, the conveyance is charged with ad valorem duty calculated on the total amount which will or may, according to the terms of sale, become payable during the