These came with a magic lantern I had and I forgot they were in the cabinet. A couple of them appear to have been purchased slides. Some appear to have been processed to hold the owners vacation slides from 1954 (boat, lighthouse, etc). A couple seem to have been home made for 'special effects'. Looks like about 15 slides and 3 'special effect's slides.
Glass measures 3.25" x 4" and then there are some little things as well. Free for $6 shipping. I'll have to get a small flat rate box from the post office, so these might take a couple of days to ship out.