Fart Lights

Besides smelling like an animal has crawled up inside you and died, farting isn’t really something most of us think about in depth. Unless you have some medical condition, your thought process probably goes from ‘hope no one smells it’ to ‘holy shit what is that?!’

Some of us have even been known to force those within close proximity to bathe in our own musk.

But farting is the natural release of gases from our bodies, gases including oxygen, nitrogen, carbon dioxide, hydrogen, and methane are expelled when we fart. Of these gases, hydrogen and methane are flammable and if enough is produced, can be ignited.

So, what does this have to do with Dunedin? I hear you ask.


This is a story of how one man’s desire to spend a whole lot of money on his dream home, turned out to be the catalyst for some pretty innovative technology being introduced to little ‘ole’ New Zealand.

Bear with me…

Driving along Highcliff road from Dunedin, it is easy to imagine yourself driving through lush Scottish hillsides, accepting how the first Scottish migrants felt when they arrived; that they had arrived in a ‘new Scotland’.

Welcome to the story Mr William James Mudie Larnach; banker, politician, merchant trader, land speculator, farmer, all round good guy (depending on who you talk to), Australian born Scotsman and family man.

For those who have no idea who I am talking about, William Larnach is famous for building his family home ‘The Camp’, more commonly known as ‘Larnach Castle’, New Zealand’s only castle, situated 13 km’s from central Dunedin.

Built in 1871 for his beloved first wife, Eliza, it took more than 200 workmen three years to build the exterior and a further 12 years for master craftsman to embellish the interior. It’s pretty flash, even by today’s standards.


Today, sitting a top of the hill, in front of a beautifully manicured lawn, surrounded by an internationally recognized garden, on a beautiful summers day, it is easy to see why Larnach Castle is one of Dunedin’s must do activities and why William Larnach chose this final spot for his magnificent home. Sparing no expense for his dream home (The original cost of construction was widely reported to be between £100,000 – £150,000 which converted into today’s money is somewhere between $600 – $900 million), he imported some of the finest materials available from all the around the world, including some unique technology.

Again, what does this have to do with farting?

Lets break it down:

We fart, out comes methane, methane can be lit, therefore methane is a form of biogas. Gas lanterns were common place in public areas during the Victorian era, the time of Larnach, but still residential homes were lit using candles and oil lamps. Therefore, using methane as a form of gas to fuel lanterns was a possibility, just the technology wasn’t common place…..yet.

Now the Chinese knew this, Chinese records dating back 1,700 years note the use of natural gas in homes and palaces for light and heat via bamboo. So, they knew that this relatively common gas could be pretty useful.

But how?

Methane gas is produced by a process termed anaerobic digestion. Anaerobic digestion is carried out by a range of bacteria in the absence of oxygen. Initially carbon dioxide is produced aerobically by the decomposing organic matter until an anaerobic environment is created. After the initial digestion, a group of bacteria known as methanogens convert the feedstock into methane and carbon dioxide gas.

Now Larnach, back to him, he had great respect for the large number of Chinese migrants arriving in Dunedin to find their fortune during the Otago gold rush. He advocated for their rights and improved working conditions while gaining the highest respect from the Chinese aristocracy. It is believed that through his associations with the Chinese diplomats and politicians, he gained the knowledge of this methane gas/anaerobic digestion technology, that they brought over from their homeland and implemented it into the design of his family home.

More than a hundred years ago, in 1886, horse manure was piped underground from the stable to a purpose-built glass chamber outside, directly behind the music room (there’s nothing more romantic than listening to some classic piano while over looking glass chambers filled with s**t). Wanting to cover all of his bases, above this, Larnach built a privy for the use of his family and staff so human manure was added to the brew.

The resulting methane gas was captured in a glass bubble and pumped up to the castle via lead pipes by a servant boy working a foot pump and used to light the chandeliers. You read it right folks, horse and human manure was collected, went through the process of anaerobic digestion, pumped by a little servant boy, lit and voila! we have light!

At the time, this type of technology was unheard of outside of China, so you can imagine the public fascination with the concept of turning your bowel movements and flatulence into a form of lighting, but Larnach did it and he did it well. This was the first residential house in New Zealand to use methane gas as a form of lighting.

So, next time you end up visiting Larnach castle, crack a good fart and spare a thought for that poor servant boy. If ever you feel the need to complain about your job again, just think, it’s probably not as bad as having the job of manually foot pumping farts around a castle.

So there you have it, the first blog on the random science behind some of Dunedin’s most popular spots, I hope you enjoyed it.

Till next time.


Featured images are authors own, taken in Larnach Castle.

Gif sourced from viagiphy https://media.giphy.com/media/XC9yzAVKsTclO





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