The provision of law under which the charge is sought to be imposed is section 10(2)(vii) of the Indian Income tax Act, 1922, hereinafter referred to as the Act, and that is, omitting what is not relevant, as follows: "(2) Such profits or gains shall be computed after making the following allowances, namely: (vii) in respect of any such building, machinery or plant which has been sold or discarded or demolished or destroyed, the amount by which the written down value thereof exceeds the amount for which the building, machinery or plant, as the case may be, is actually sold or its scrap value: Provided further that where any insurance, salvage or compensation moneys are received in respect of any such building, machinery or plant as aforesaid, and the amount of such moneys exceeds the difference between the written down value and the scrap value no amount shall be allowable under this clause and so much of the excess as does not exceed the difference between the original cost and the written down value less the scrap value shall be deemed to be profits of the previous year in which such moneys were received:".