The most common forms of treacle are the pale syrup known as golden syrup and the darker syrup usually referred to as dark or black treacle. Dark treacle has a distinctively strong, slightly bitter flavor, and a richer color than golden syrup, yet not as dark as molasses. Golden syrup is the main sweetener in treacle tart.
Historically, the Middle English term triacle was used by herbalists and apothecaries to describe a medicine (also called theriac or theriaca), composed of many ingredients, that was used as an antidote treatment for poisons, snakebites or various ailments. Triacle comes from the Old French triacle, in turn from (unattested and reconstructed) Vulgar Latin triacula, which comes from Latin theriaca, the latinisation of the Greek θηριακή (thēriakē), the feminine of θηριακός (thēriakos), "concerning venomous beasts", which comes from θηρίον (thērion), "wild animal, beast".
Treacle is made from the syrup that remains after sugar is refined. Raw sugars are first treated in a process called affination. When dissolved, the resulting liquor contains the minimum of dissolved non-sugars to be removed by treatment with activated carbon or bone char. The dark-colored washings[clarification needed] are treated separately, without carbon or bone char. They are boiled to grain (i.e. until sugar crystals precipitate out) in a vacuum pan, forming a low-grade massecuite (boiled mass) which is centrifuged, yielding a brown sugar and a liquid by-product—treacle.
In popular culture 
At Halloween, especially in Scotland, a traditional task visiting children had to accomplish in order to win their treat, was to eat a scone spread with treacle ('treacle scone') which was suspended on a piece of string at about head height. They had to do so without using their hands, resulting in treacle covered faces.
In chapter 7 of Lewis Carroll's Alice's Adventures in Wonderland, the Dormouse tells a story of Elsie, Lacie and Tillie living at the bottom of a well, which confuses Alice, who interrupts to ask. "The Dormouse again took a minute or two to think about it, and then said, 'It was a treacle-well.'" This is an allusion to the so-called "treacle well", the curative St. Frideswide's Well at Binsey, Oxfordshire.
In the 1946 novel by P. G. Wodehouse, Joy in the morning, Bertie Wooster attempts to use treacle and brown paper to muffle the sound of broken glass while trying to fake a robbery at the home of his Aunt Agatha and her husband, Lord Worplesdon.
In the film Around the World in 80 Days (1956 film), Phileas Fogg tells the steward on the RMS Mongolia from Suez to India that his Thursday mid-day meal "has always been, and will always be, hot soup, fried sole, roast beef and Yorkshire Pudding, baked potato, suet pudding and treacle".
In the film Chitty Chitty Bang Bang, the "Child Catcher" uses the promise of free Treacle Tarts as one of the lures to capture the Potts children. When Jeremy Potts hears "Treacle Tarts" among the list of treats promised, he exclaims "Treacle Tarts!"
In Hugh Lofting's book The Voyages of Doctor Dolittle it was mentioned by Tommy Stubbins that treacle tart is one of Doctor John Dolittle's favorite dishes. They also took with them "20 pounds of treacle" on their voyage to Spider-Monkey Island. A treacle mine features in the novels Reaper Man (1987) and Night Watch (2002) by Terry Pratchett. In the fictional Discworld city of Ankh-Morpork there is a street named Treacle Mine Road, with the current watch house (analogous to a police station) found in the building formerly housing the entrance to a treacle mine.
In the second season of Thomas the Tank Engine and Friends episode titled Wooly Bear, Percy the Green Engine was hit with a box of treacle.
In "The Funk Hole," episode 4, season 2 of the Masterpiece television series Foyle's War, Sam complains that due to wartime food rationing, she has resorted to putting treacle in her tea. "It tastes quite disgusting," she says, "and it goes over black so it looks disgusting too."
'Treacle' is a term of endearment, from Cockney rhyming slang: sweetheart = treacle tart. In the BBC soap opera EastEnders, former character Pete Beale often addressed Sharon Watts as 'treacle'. "Black Treacle" is a song by the English indie rock band Arctic Monkeys, released as the fourth single from their fourth studio album Suck It and See. Treacle Tart is also mentioned frequently in the Harry Potter book series by J.K. Rowling as Harry Potter's favorite dessert.
See also 
- Treacle mining
- Treacle protein
- Treacle sponge pudding
- Venice treacle, also known as Treacle of Andromachus
- "Treacle Origins and Uses at www.recipes4us.co.uk".
- Oxford Dictionary ISBN 978-1-85152-101-2
- theriacus, Charlton T. Lewis, Charles Short, A Latin Dictionary, on Perseus
- θηριακός, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
- θηρίον, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
- Treacle, on Oxford Dictionaries
- Heriot p 392
- p14, Oxford in English literature: the making, and undoing, of "the English Athens" (1998), John Dougill, University of Michigan Press, ISBN 0-472-10784-4.
- See pages 61 and 63 of 4:50 From Paddington: A Miss Marple Mystery by Agatha Christie (New York, New York: Black Dog & Leventhal Publishers, 2007). Available on-line at: 4:50 from Paddington: a Miss Marple mystery.
- Heriot, Thomas Hawkins Percy (1920). The manufacture of sugar from the cane and beet. London: Longmans, Green and co.