S. A. HAKEEM, J. - The common petitioner in these petitions is a registered dealer under the Karnataka Sales Tax Act, 1957 ("the Act"). The petitioner purchases iron scrap from dealers for the purpose of manufacturing iron and steel castings which are sold by it. For the assessment years 1973 and 1974 ending December 31, 1973 and December 31, 1974 respectively, the petitioner filed its annual returns declaring certain turnover and claiming exemption of sales turnover of the manufactured goods. Accepting the contention of the assessee that the goods sold were manufactured out of tax-suffered iron scrap, the Assistant Commissioner of Commercial Taxes (Assessment), Mysore, exempted the said sales turnover of manufactured goods. Later, the assessing authority, in exercise of his power conferred under section 25A of the Act, issued notice to the petitioner proposing to rectify the alleged mistake apparent on the record on the ground that the deduction allowed on the sale of castings and ingots manufactured out of iron scrap ought not to have been allowed. The petitioner took the contention that the sale of castings and ingots had been duly exempted under the Government order da