I just moved into a home build in the late 1800s and the stone foundation and bricks in the chimney (from the basement up to the top of the second floor) are eroding away (flakes and piles of shedded mortor/stones in the basement and mortor and sand-sized pieces of brick collected on all adjacent floors). I assume that this is due to the amount of lime in the mortor that was used in that time period breaking down.

In addition to repointing the concrete is there anything else I can brush on these surfaces (especially the bricks) to prevent this from continuing?