On Thursday I won a group of insulators in a local online auction. From the pictures I knew one of them was a 133.1 Electrical Supply Co, and there was also a PRR, some postal star beehives, and a couple of signals. All of them were black with soot. I assumed the PRR was glass but when we picked them up yesterday, I discovered it was porcelain, although so black you couldn't tell without turning it over. I soaked everything in acid overnight. What a surprise when, while I was scrubbing the soot off the PRR....I saw letters appearing on the dome. With all of the dozens of these porcelain PRRs I have acquired in auctions and collection purchases, this is the first one that has ever been marked. That was very exciting for me.