Gaslight

As an urban kid, my first encounter with the will-o’-the-wisp was through literature. In the dreary journey to Mordor in The Lord of the Rings, Frodo and Sam make their way through the Dead Marshes; Gollum warns them not to follow the lights that can lead them astray. For Harry Potter readers, the equivalent creature is the hinkypunk. Wikipedia defines it as an “atmospheric ghost light… dancing or flowing in a static form, until noticed or followed, in which case they visually fade or disappear”. Today, their lore has been transformed into the kid-friendly version of the jack-o’-lantern at Halloween.

 

We now know something about the chemistry that causes this luminescence – oxidation reactions involving methane and phosphines, gases released in marshland from decaying organic matter. Air currents play a role in the wispy behavior. While I’ve personally never seen this before – I don’t visit marshlands in poorly lighted areas – it is apparently spooky-looking. In his latest book, It’s a Gas, author Mark Miodownik shares historical writings about such spooky observations. I learned that a Major Blesson, from Napoleon’s army, did some early experiments to figure out what was going on and concluded that the wisps were “caused by flammable gas bubbling up from the bottom of the marsh”.

 

Living in an age of electric lights in urban areas, I have scant notion of what it would really be like to have experienced what most of humanity knew when the sun went down. Darkness. Danger. And the fear of not being able to see what might be lurking nearby. (Yes, I could go camping in some remote area to see the stars, but I like my creature comforts.) Miodownik discusses the “anatomy of a flame” from a wood fire, and how careful observations led to mass production of charcoal and tar. Folks also discovered that the invisible released gas was also explosive: Methane. In the marshes we can thank anaerobic microorganisms that eat carbon dioxide and poop methane.

 

Enter the scientists and engineers: Could methane gas be used to light the streets and households of urban areas? Can we shoo away the dark and eliminate the spooky? It was also a safety issue. You might fall into a cesspool or get mugged. In 1801, the inventor Philippe Lebon rigged a system for a hotel in Paris. According to Miodownik, “so marvelous was the spectacle of will-o’-the-wisps flickering away around every corner that the public happily paid three francs to enter and see the wonderland he had created.” But that first system didn’t catch on. It was the stink. Not from odorless methane, but from small amounts of hydrogen sulfide that were naturally part of the gas mix. British engineers eventually figured out how to remove the stink: one step in their refining process involved bubbling the gas mixture through lime water (calcium hydroxide solution) which reacts with acidic hydrogen sulfide.

 

Storing gas was a tricky business. You had to compress it. Then you had to release it at the right pressure to get optimal lighting while avoid too many fumes from incomplete burning. Then there was the problem of gas leaks. Today, a tiny amount of methanethiol, a compound very similar to hydrogen sulfide, is added so our noses can detect the smell of a gas leak. In a mere 25 years after Lebon’s demonstration, any large town in Britain had gaslight. Eventually gaslight was replaced by electric light as science marched onward.

 

The word gaslight has returned to our vocabulary in the twenty-first century. As women entered the workforce in ever-increasing numbers and began to vie for positions in leadership, boorish men took to “gaslighting” them. Miodownik relates that the phrase coms from a 1938 play titled Gaslight whereby a conniving husband tries to manipulate his wife into thinking she is insane “by dimming the gaslights in their home, and when she notices, he claims the lights are not dimmer – it is all in her mind.” In a former age, gaslight illuminated. Now it obscures. What will it do in tomorrow’s age?