Fourteenth. No merchant, store-keeper or dealer shall keep for sale or sell pistols, Springfield rifles, repeating rifles, bowie knives or dirk knives, without first paying a license tax of ten dollars; Provided, Said pistols, Springfield rifles, repeating rifles, bowie knives or dirk knives, shall not be sold to minors. Every violation of this paragraph shall he punished by a fine of fifty dollars, or by imprisonment in the county jail not more than six months.