Said mayor and common council shall have full power and authority . . . to regulate the storage of gunpowder and other combustible materials . . . .

Ordinances [of Boise City], Storing of Powder, § 31. It shall be unlawful for any person or persons, firm, corporation or association to keep or store in any building, store or warehouse, within the corporate limits of Boise City any gunpowder or blasting powder in greater quantities than fifty pounds; or for any person, firm, association or corporation to keep within the corporate limits of Boise City any giant powder, nitro-glycerine, gun cotton, Herculese powder, dynamite or other material or substance of equal explosive force by whatever name known. Penalty. § 32. Any person or persons violating the provisions of …