I am more familiar with plaster walls, but have found that one of the key fixes is to stop all air infiltration first, and then consider insulation as the 2nd step. If you seal around all exterior wall penetrations (receptacle and switch boxes, between shiplap boards, etc.) it should help quite a bit. Walls may still be cool/cold to the touch, but with no air movement and relatively thick interior walls, the cold infiltration / transmission will be slow. Then spend money on upgrading attic insulation, and start budgeting for more energy efficient windows.

My 1940 house does not have any insulation in the exterior walls (brick facing, 2x4 framing, plaster walls), but I have high quality attic insulation. We experience temps down to the teens and sometimes lower, and keeping the house warm is not an issue.

I would never consider adding some type of surface insulation (cork?) to 1900 interior walls, It would probably need to be glued, and there will be very little possibility of ever returning the walls to their original condition.

Bruce

I agree with Bruce that you shouldn't do this: it's a bad idea practically and aesthetically, and it won't save much energy. My suggestion is to contact your local utility and have an energy assessment done of your home. These days most utilities have a department staffed with "energy auditors" who will do this for free, and can give you an idea of which measures will give you the most bang for your buck. Some even finance such energy improvements and/or give rebates. If your house is not insulated, some of the improvements will pay for themselves in a year or two. Once you're past that breakeven point, you'll keep saving money each year.