VENKATARAMA AYYAR, J.

These writs raise the question of the validity of the Madras General Sales Tax Act (IX of 1939) and of the Turnover and Assessment Rules, 1939, framed thereunder hereinafter called the Rules. The petitioners in Writ Petitioners No. 21 of 1952 are doing business as tanners in Eluru. The course of business is that they purchase raw hides and skins and tan them in their own tannery. They hold a licence as tanners under the Act. Under Rule 15, they were submitting monthly returns of hides and skins purchased by them for the purpose of tanning in From No. A-4 and an order was passed on 23rd February, 1951, on the basis of these returns determining the tax payable at Rs. 10-180-7-3. Payments amounting to 4, 790-13-0 had been made by the petitioners towards the amount of the tax and for the balance of Rs. 5, 389-10-3 remaining payable, a demand was duly made by notice under Rule 15(4). No appeal was taken against the order of assessment and it has become final. Nor was any action instituted to contest its validity. The tax not having been paid, the Commercial Tax Officer instituted proceedings under Section 15(b) of the Act for the recovery of the amount.