PART XII
137. In regard to any receptacle, the following provisions shall be observed:
(a) it shall be provided with a closely fitting lid secured by a lock, and hinges and fastenings, preferably of copper or brass, and otherwise closed and secured so as to prevent unauthorized persons having access thereto, and shall be kept locked except when required to be open for receipt or removal of explosives, or other necessary purpose;
(b) it shall be exclusively used for the keeping of explosives;
(c) it shall be made of wood, copper or other suitable material;
(d) the interior of the receptacle and all fittings therein shall be so constructed, covered or lined as to prevent the exposure of any iron or steel, or of any hard or gritty surface, or the entry, detaching, or accumulating of grit, iron, steel or similar substance;
(e) the interior of the receptacle shall be kept scrupulously clean; and
(f) the receptacle shall have the word “EXPLOSIVES” conspicuously displayed thereon on a contrasting background.