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Established in the 1830s in Massachusetts, the Florence Knitting Mills were a division of the Nonotuck Silk Company. The company was known to produce a number of instructional books which were meant to explain how to use their knitting silk to create articles of clothing.
Like most companies of the time, the Florence Knitting Mills produced trade cards--just like the one pictured above--and, like most American cards, there’s nothing printed on the reverse. The obverse simply shows an attractive image with the company’s slogan: “FLORENCE, THE SOFT FINISH, PEERLESS KNITTING SILK.” Pictured is a bespectacled woman who appears to be making a red glove. Meanwhile, her cat (soft kitty, warm kitty, little ball of fur) has stolen some of her Florence Knitting Silk—presumably from the inset picture of the product—to use for his own feline purposes.
I'd place this as having been printed around 1885.