This is the first of my images from negatives that I processed using Divided Pyrocat HD which is supposed to give a compensating effect to high contrast situations, although I normally use Pyrocat HD in its mixed form I thought I would try the divided Pyrocat HD as I wanted to get some detail from the semi-circle window. I am very pleased with the compensating effect, I could not believe the amount of detail from the semi-circular windows bearing in mind how high the contrast between the light outside and the very dark conditions inside.
The measured exposure was 30 secs @ f45 at ISO25, although the exposure I actually gave was 4 minutes at f45 on Adox CHS25 which will give an idea of how dark it was although I did allow 1 stop for reciprocity and I also had the Centre Filter on the 72mm Super Angulon XL which ate up another 2 stops.

Redundant Pressure Filters (Tottiford Water Treatment Works) by Ed Bray, on Flickr