( 1 ) THIS group of petitions is referred to this Bench to decide the question whether the petition abates on the grounds mentioned in the affidavit of the respondents. These petitioner were filed by the peti- tioner-mill companies which are cotton textile units manufacturing blended yarn which became dutiable for the first time under Tariff Item 18-E which was added on March 16 1972 in the Central Excise and Salt Act 1944 (thereinafter referred to as the Act ). It is the case of the petitioners that blended yarn was coated with sizing materials to impart strength to the yarn in the weaving process in all these composite mills and in that process the weight of the blended yarn increased by some 12 to 14 per cent. It is the case of the petitioners that blended yarn remained blended yarn even after the sizing process. The excise duly was paid on the sizing materials. In all these mills the duty was charged by the excise authorities under Tariff Item 18-E on weight basis per kilogram of unsized yarn that is to say at the spindle point. However by the Trade Notice issued by the Deputy Collector of Central Excise No. 195/76 dated August 9 1976 a change of basis had been a