RogerT wrote:
John Grabowski wrote:
It sounds as though you have terracotta block. You can fish wires
through that if there isn't too much residual cement and debris
inside. You would have to cut holes for the boxes and then cement
them in place. The terracotta block can be hard. You may need an
angle grinder with a diamond blade to cut through it neatly. Instead
of cable, you could use flexible conduit to feed the box so that you
can add or replace wires down the road without having to remove the
box.

It does look like terracotta blocks to me. If I get a chance, I'll
try to get a good picture of it and post it. It is very easy to cut
and/or break out, partly because the blocks are hollow. I already
had to do that in a few areas for other work I was doing

Here are two photos I took that show the terracotta blocks:

http://i52.tinypic.com/29mnbk4.jpg

http://i55.tinypic.com/ygw9s.jpg

The first photo shows the dividing wall between the two properties. The
blocks in the center are for a dual chimney -- one for each of the two
properties. One either side of the chimney are the blocks for the actual
dividing wall. The chimney originally had framing just around that part.
Then a later owner must have framed out a wider section from the front wall
of the property (on the right) back past the chimney. So, on the sides, you
can see the old wallpaper before the newer framing covered it up. Where the
wallpaper is, it is just rough coat and finish coat plaster directly over
the block (like the rest of the exterior walls), then wallpaper on top of
the plaster. On the right is one of the cast iron radiators that is under
the front window.

The second photo is uptairs in another part of the house. It shows what
used to be another no-longer-used chimney chase -- which is also on the
dividing wall between the two properties. I knocked out the chimney way on
my side, and the only point of this picture is to show how the terracotta
blocks are hollow by showing some of the broken off blocks.