§ 3. "That the new import duties which zero imposed by Part I of the Finance (No. 2) Act, 1915, shall be revived and shall be charged on and after the first day of July, nineteen hundred and twenty-five, and for the purpose of the charge of duty on cinematograph films the expressions 'positives' and 'negatives' in Section twelve of the said Act shall be deemed respectively to include undeveloped positives and undeveloped negatives "