( 1 ) THIS Rule was directed against the petitioner's conviction under Section 407 read with Section 488, Calcutta Municipal Act, 1923, for having sold adulterated mustard oil. The prosecution case was based upon an analysis of a sample of the oil concerned disclosing' a saponification value of 177,8. The petitioner's defence was thai the oil was pure.

( 2 ) THE validity of the conviction depends upon the construction to be placed upon the relative words of two Government Notifications, numbered respectively 735 P. H. and 736 P. H. , both dated 20-3-1928, issued in exercise of the power conferred by Section 422 of the Act.

( 3 ) THE material part of Section 407 of the Act is in these terms:"407 (1) No person shall directly or indirectly, himself or by any other person on his behalf, sell, expose or hawk about for sale, or manufacture or store for sale, any of the following articles, namely,. . . . . (e) mustard oil,. . . . . unless the following conditions are fulfilled, namely,. . . . . (v) in the case of mustard oil it shall be derived exclusively from mustard seed;"it is clear from the section that what is prohibited is the sale etc. of mustard oil which is not der