How The Pressure Cooker Inspired The Steam Engine

Dec 12, 2022 0 comments

For nearly 200 years, the steam engine powered the world’s machineries, but its origins were very humble. It began with the pressure cooker, or more precisely, its predecessor the ‘steam digester’, invented by a long forgotten Frenchman named Denis Papin.

Denis Papin was born in the village of Chitenay, near Blois, in 1647. He attended the University of Angers, from which he graduated with a medical degree in 1669. However, Papin was not destined to practice medicine. After he moved to Paris, Papin met and befriended Christiaan Huygens, the famous Dutch polymath, and the duo conducted many experiments with an air pump and vacuum. The most memorable of these experiments was a ‘gunpowder engine’, a machine where gunpowder was lighted inside a cylinder and the expanding gases from the explosion was allowed to escape. This created a vacuum strong enough to lift ‘seven or eight’ boys using just a couple of grams of gunpowder.

Photo: Cantons-de-l'Est/Wikimedia

After publishing the results of these tests in 1674, Papin moved on to England and became assistant to the famous Irish chemist and inventor Robert Boyle. Together, they conducted many experiments in magnetism, blood chemistry and respiration, but especially with the air pump.

In 1679, Papin developed what he called a ‘steam digester’, which he described in a brochure titled “A New Digester for Softening Bones containing the Description of its Make and Use in these Particulars viz. Cookery, Voyages at Sea, Confectionary, Making of Drinks, Chymistry, and Dying with an Account of the price a Good Big Engine will cost and of the Profit it will afford.” As the rather verbose title indicates, this little treatise simultaneously served as a construction guide, an experiment log, and a cookbook, where he detailed his success in cooking mutton, beef, lamb, rabbits, pigeons and making various jellies from fruit and animal byproducts.

The digester was made from two hollow brass cylinders pressed together by screws. Food could be placed in an inner glass sleeve and cooked under pressure. Most notably, the device featured a safety valve consisting of a flap of leather held down by a weighted rod. When pressure rose too high, the safety valve was forced open and steam escaped until the pressure dropped sufficient for the weight to close the valve again.

The Steam Digester.

The digester was so named because it not only cooked food but also softened bones for the production of fertilizers. “The mutton was very well done, the bones soft, and the juice a strong Gelly,” wrote Papin, describing the results of one of his experiments. The book also included many recipes for cooks and confectioners to try, many of which could still be tried today with a modern pressure cooker.

On April 12, 1682, Papin put his Digester to test by preparing an elaborate meal for the members of the Royal Society of London. Member John Evelyn recorded the experience in his diary:

I went this afternoon with several of the Royal Society to a supper which was all dressed, both fish and flesh, in Monsieur Papin's digestors, by which the hardest bones of beef itself, and mutton, were made as soft as cheese, without water or other liquor, and with less than eight ounces of coals, producing an incredible quantity of gravy; and for close of all, a jelly made of the bones of beef, the best for clearness and good relish, and the most delicious that I had ever seen, or tasted. We eat pike and other fish bones, and all without impediment; but nothing exceeded the pigeons, which tasted just as if baked in a pie, all these being stewed in their own juice, without any addition of water save what swam about the digestor, as in balneo; the natural juice of all these provisions acting on the grosser substances, reduced the hardest bones to tenderness.

Papin soon realized that his digester could have wider application outside the kitchen. In 1690, Papin combined his digester with the earlier idea of a gunpowder engine and designed a prototype steam engine. This machine was similar to the gunpowder engine but instead of gunpowder, Papin put a small quantity of water and placed a fire under the engine. The resultant steam drove a piston upwards where it was held in place by a latch. Once the steam condensed, a vacuum was produced in the cylinder, which pulled the piston down engaging a rope and pully system to lift a weight of 60 pounds per minute. Papin calculated that a larger machine could raise as much as 8,000 pounds four feet per minute.

Papin demonstrating his steam pump before the Royal Society of London.

Papin claimed that his engine would help pumping out water in mines, in throwing bombs and in ship propulsion. Papin also described a new furnace, a kind of fire-box steam boiler, in which the fire, completely surrounded by water, makes steam so rapidly that his engine could be driven at the rate of four strokes per minute by the steam supplied. Papin never built his machine, which would have been the first steam-powered piston engine, the kind that drove the Industrial Revolution.

Papin died in 1713. One year prior, an English inventor named Thomas Newcomen brought together most of the essential elements established by Papin in order to develop the first practical steam engine—a pump to lift water out of mines. Although heavy on fuel, Newcomen’s machine was such a runaway success that it was installed in mines across England.

Denis Papin

We don’t know whether Papin was aware of Newcomen’s invention, which drew so heavily on his ideas. At the time of his death, Papin was living in London, in poverty and in obscurity. He had discovered that several of his papers were put before the Royal Society without acknowledging or paying him, which left him bitter and disheartened. The last evidence of Papin's whereabouts was a letter he wrote dated January 23, 1712. It was believed that Papin died that year, until a record for a burial was discovered in an 18th-century Register of Marriages & Burials at the London Metropolitan Archives. In 2016, a memorial plaque was erected on the grounds of St Bride's Church, in London to commemorate his life and his achievements.

References:
# Daniel Crown, “The Instant Pot of the 1600s Was Known as ‘the Digester of Bones’”, Atlas Obscura
# Robert Henry Thurston, “A History of the Growth of the Steam-engine”
# John Evelyn, “Diary and Correspondence of John Evelyn”

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