These are two identical exemplars, neither inventoried nor signed, in which the characteristic glass jar used in the Leyden jar is actually a bottle (25 cm in height) with a very narrow neck filled with softly rolled and folded foil.
The bottom and sides up to a certain point on the outside are lined with foil, while the rest is covered with a thin insulating layer of shellac.
The bottle is closed with a cork sealed with sealing wax. A brass conducting rod penetrates through it; on the outside this rod is bent into a hook and ends with a small ball, while the end inside the bottle has some thin metal reeds resting on the foil inside glued to it.
The Leyden jar is a condenser in which the outside plate is composed of the foil glued to the bottom and sides of the jar; the inside plate is the foil contained in it and the dielectric is the glass.