What a cast of characters! I've come across old Magic Lantern slides before, but none as wonderful as these, charmingly caricaturing a variety of couples, while imparting each figure with fantastic personality! Reverse painted on glass (I believe etched in black first, then with all the color painted by hand) in a terrifically bright palette of pinks, yellows, greens and blues, they really pop against the unpainted (clear) glass backgrounds, framed with light green paper. While great just as objects, these are especially well suited for mounting and framing. Just fabulous.
The closest matches to these I've found are French, held in the collection of the Corning Museum of Glass. I would guess French on these, too, though a little earlier, maybe 1880s. During the 2nd half of the19th century, hand-painted slides began to be replaced by photographic slides, and by the end of the 19th century the magic lantern was overtaken by the cinematograph, projecting "living pictures." Much more about the history of Magic Lanterns here.
These slides are in excellent condition, with almost no loss of paint or paper on the frames. Each slide measures 9 3/4 long x 2 3/4" tall x 1/16" thick. I'm listing them as a set of 4 as I think they are really wonderful all together, but might later consider breaking up if I can't sell as a group.