Hence the liability of the assessee which had become fixed under Act XV of 1948, as it originally stood, could not be and 'Was not varied by section 3(A) and would not therefore be affected by any notification issued under the last mentioned provision ; (3) that a notification under section 3(A) could not have retrospective effect since section 3(A) itself did not operate of its own force and merely empowered the Government, 'by a notification, to effect changes in the law and hence such changes when notified could not operate as from any date prior to the date of the notification ; (4) Section 3(A) which used the words " in respect of such sales " contemplated particular sales taking place after the notification issued under it and hence the notification issued under that section could not alter the rate of levy in respect of sales anterior to the date of the notification ; (5) that the terms of the notification carried out the general scheme of the Act and negatived retrospective operation and that as on its langu age it applied only to sales which took place on or 205 admittedly effected long prior thereto in the previous year the same could not be affected by the enhanced rate of duty.