No person shall engage in the business of a junk dealer for the purchase or sale of what is commonly called junk, such as rags, paper, bags, bagging, iron, brass, copper, tin, zinc, aluminum, scrap or discarded metal, bottles or other articles, whether manufactured or in the process of manufacture of such material, and whether old or new, and no person shall transport through the streets or alleys of the City any conveyance for the purpose of collecting or disposing of such articles, without first obtaining a license therefor from the City Clerk as provided in this chapter.