It shall be unlawful for any city, borough, or municipality, to levy any license or mercantile tax upon persons taking orders for merchandise by sample from dealers for individuals or companies who pay a license or mercantile tax at their chief places of business. It shall also be unlawful for any city, borough, or municipality to collect such license or mercantile tax hereafter, levied by virtue of any ordinance of any city, borough, or municipality: Provided, That nothing in this act shall authorize such person to sell by retail, to others than dealers or merchants.
72 P.S. § 6181