Old toilet vents

What are you talking about? Your plumbing vents run into a chimney? You want to crimp the pipe (how) and tape it off (why). Get a plumbers advice on what should be done as this sounds all wrong!

You have to have toilets vented somehow!!!!

I would take it out of the chimney. Some day the chimney will be full of methane when the furnace comes on and you will be picking bricks out of your teeth.

Thanks for the responses. I guess I need to explain what I have a little better. Behind the tanks of all three toilets are the ends of these vents. And I guess I am assuming that these are vents. The ends are stuffed with rags and haven't been used for God knows how long. And again two vents merge in the attic and go out the chimney. The third goes out the roof. I don't know how these were connected to the toilets back in the day. Surely others must have come across vents such as these. Does this help at all? Thanks.

Yes, they were installed for venting of room air, rather than as part of the DWV vent system. Precursor to the modern bath vent fan.

Rather an upscale feature in 1924, I should think.

You could install a sheet (sheet metal or other) behind the vent grill to permanently stop loss of conditioned air from the bath(s). Mortar up the chimney opening (presumably uses a separate chase from the heating equipment).

Again it is someone using wrong terminology to describe their problem. They know enough terms to thoroughly confuse anyone who believes the person is describing a problem with the item they are referring to.

A problem with a "toilet vent" immediately brings to mind the "Drain, Waste & Vent" DWV plumbing system, where the original poster is describing a bathroom ventilation duct. It has nothing to do with the toilet other than being near it to remove smells. Confusion, confusion -- a good thing that someone finally clued into what the OP is talking about because it made no sense to me when I read it.