The Madras Rubber Factory Ltd., the petitioner herein, has filed this writ petition for the issue of a writ of prohibition restraining the Assistant Collector of Central Excise, Madras, the first respondent herein, from taking any further proceedings in pursuance of the show cause notice No. V/16A/18/1/78/T. 2, dated 28-2-1978. The facts leading to the filing of the writ petition may be stated as follows : The petitioner manufactures passenger car tyres, truck tyres, tubes, tread rubber and other allied products. The petitioner has been marketing tread rubber in metal containers. With effect from 1-6-1968, tread rubber became assessable to excise duty onad valorembasis under the provisions of the Central Excises and Salt Act, 1944 (hereinafter called the Act) and the petitioner has been paying the said duty on the tread rubber. In the beginning the price list submitted by the petitioner for tread rubber for purposes of assessment of excise duty included the value of the metal container also. The price of the metal container as certified by the Costs Accountant came to 52 paise in the value of tread rubber for 1 K.G. In 1970 the petitioner took the stand before the Centr