The South Meadow generating station was operated by the Hartford Electric Company in Hartford, CT. The unit described in the 1931 Pop Sci article used 90 tons of mercury in the boiler. The article states that the South Meadow generator produced as much as 143 kWh from 100 lbs of coal, as opposed to an average of 59 kWh from conventional coal fired plants and 112 kWh from exceptionally efficient coal fired plants. The article describes an incident at the plant where a breech of containment from an explosion in the mercury vapor system occurred, releasing mercury and exposing workers to mercury vapor.
The Schiller Mercury Power Station in Portsmouth, NH, is described in this link.
Lamentations on Chemistry 
I’ve heard of liquid sodium as a heat transfer fluid in nuclear powered submarines, but mercury as a heat transfer fluid–WOW!
Having used a Hg diffusion pump I am familiar with Hg vapor up close and personal. The first time I fired it up I was quite nervous – there was no manual or how to video. Over time I came to really appreciate its fundamental beauty.
I think I did, however, always turn it on and leave the room until it was running …
Oh, and I need to add – it was all glass. You could see the mercury as it traveled through the pump. It had at least 20lbs of Hg in it.
As an undergrad I assisted my inorganic professor clean a large Hg spill (~300 mL) when his Toepler pump broke, spilling the contents on the floor. We scraped the floor with cardboard and then sprinkled sulfur everywhere. We sat in that room the entire next year for P-chem. No wonder I was brain damaged from the experience.
It is a very naive person, indeed, who does anything in a lab that is over 10 years old and doesn’t assume something nasty has been spilled and cleaned up.
I am sure that the labs where I did my graduate work (UF) and post-doc (WU at St. Louis) had had multiple Hg spills.
They both did have very high air turnover thanks to the hood fans.
Almost, but not quite, enough to turn one into a chemophobe…
I’m not much of a chemophobe. But I’ll tell you that a semester of microbiology in college set me on notice of that world. It’s fun to talk to people who have had a term of parasitology. That is a real eye opener.
I was just reading an article on this in an old issue of Fortune. The plant was the latest and greatest back then. What do we use now, superheated steam? It even had a mercury sensor on the exhaust stack consisting of a mercury sensitive sheet of cloth and a photosensor that would set off an alarm when the cloth turned black. That was extremely high tech back then.
South Meadow Generating Station was a welcoming sight for the traveler approaching Hartford along Route 2 from the east.
It’s magnificent stacks and rooftop steam blowdown vents were as a beacon to the roadweary.
Years ago, ca. 1980, a staffer at the plant stated the building was a shell, that all the turbines, generators and steam boilers including presumably the Hg boiler and turbine had been removed; some scrapped some shipped to unspecified points South America.
In a way South Meadow’s architecture and stack configuration resembled Providence, RI’s Manchester Street Generating Station prior to its 1994 repowering. Manchester Street’s original building was designed by Stone & Webster while the 1947 additions to the east and west side of the building were the creation of Philadelphia’s Paul Cret. It would be interesting to know who designed South Meadow, as its lines are distinctly those of Paul Cret’s Manchester Street design.
Paul Vincent Zecchino
Mansota Key, Florida
29 Auguts, 2014