(a) As used in this subchapter, unless the context otherwise requires, “illicit still” means an apparatus designed for the unlawful manufacture of intoxicating liquor, which shall include an outfit or parts of an outfit commonly used, or intended to be used, in the distillation or manufacture of spirituous, vinous, or malt liquors and which is not duly registered in the office of the Commissioner of Internal Revenue.
(b) The burden of proving that the still or apparatus is so registered shall be on the defendant or defendants under charge.