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Your Class 10 textbook says the gastric glands release hydrochloric acid, the enzyme pepsin and mucus. Two centuries ago nobody knew whether the stomach digested food chemically, ground it mechanically, or did something more mysterious. A frontier army surgeon settled much of the argument by watching a living stomach through a hole in a patient's side. This post covers what he did, the numbers in his own book, and the uncomfortable questions it raises today.
How did Beaumont get a window into a stomach?
William Beaumont (1785 to 1853, per a 1933 biographical article on PubMed Central) was a surgeon in the US Army. In his own book, Experiments and Observations on the Gastric Juice, and the Physiology of Digestion, printed in Plattsburgh in 1833, he describes being stationed at Michilimackinac, Michigan Territory, in 1822.
His patient, Alexis St. Martin, was a Canadian of French descent, about eighteen, working as a voyageur for the American Fur Company. On 6 June 1822 a musket loaded with powder and duck shot went off less than a yard from his left side. He survived. By June 1823 the wound had healed except for an opening into the stomach, which Beaumont says was about two and a half inches in circumference.
That size is easy to picture with a little geometry. Diameter = circumference ÷ π = 2.5 ÷ 3.14 ≈ 0.80 inch, and 0.80 × 2.54 ≈ 2.0 cm. Food and drink leaked out unless the opening was covered with a pad and bandage.
What did his experiments show?
The experiments began in 1825. In the first series, on 1 August 1825, Beaumont tied small pieces of different foods to a silk string and passed them into the stomach, pulling them out at intervals to see what had changed.
The most famous comparison came on 7 August 1825. After St. Martin had fasted for seventeen hours, Beaumont:
Put a thermometer into the stomach. The mercury rose to 100°F, which is (100 − 32) × 5 ÷ 9 ≈ 37.8°C.
Drew off one ounce of clear gastric juice through a rubber tube into a vial.
Added a piece of boiled salted beef weighing three drachms, corked the vial and kept it at 100°F in a water bath on a sand bath.
At the same time hung a matching piece of beef inside the stomach on a string.
In the vial, digestion had clearly started in forty minutes and the meat was completely digested by 9 o'clock that night. The piece in the stomach was gone when he pulled the string at 1 p.m. Both digested the same way, from the surface inwards, but the stomach was faster; shaking the vial also sped it up. Starting from late morning, that is roughly two hours inside the stomach against roughly ten in the vial.
What did he learn about the acid?
Beaumont was convinced that gastric juice contained free muriatic acid, the old name he himself equates with hydrochloric acid. In the winter of 1832 to 1833 he sent a sample to professors at the University of Virginia. Their letter, reproduced in his book and dated 6 February 1833, reported free muriatic and acetic acid, phosphates and chlorides of potassium, sodium, magnesium and calcium, and an animal matter soluble in cold water but not in hot.
NCERT Class 10, Chapter 5 (Reprint 2026-27) gives today's version: gastric glands release hydrochloric acid, pepsin and mucus, and the acid creates the acidic medium pepsin needs. Digestion and absorption is no longer a chapter in rationalised NCERT Class 11 and is not in the NEET-UG 2026 syllabus, but it matters for Class 10 boards; check your current syllabus.
Was it ethical?
St. Martin left in 1825 and later returned. Beaumont writes that in August 1829 St. Martin came with his wife and two children to Fort Crawford, Prairie du Chien, and entered his service; experiments continued, with interruptions, until March 1831, while St. Martin also chopped wood and carried loads as a servant.
The historian Alexa Green analysed this relationship in the Bulletin of the History of Medicine. She argues their arrangement was shaped by models of employment, servitude, contract labour and military service, not by research ethics as we know them. Today a study like this would need informed consent and approval from an ethics committee.
Common mistakes:
Thinking Beaumont discovered pepsin. His book identifies acids and an "animal matter"; NCERT names the enzyme.
Converting 100°F wrongly. Subtract 32 first, then multiply by 5/9.
Forgetting the control. Without the vial, he could not separate chemistry from the stomach's movements.
What can a student take from Beaumont?
He kept dated, timed notes and repeated observations under changed conditions, and he set up a comparison outside the body to test a single idea. The same habit helps with any experiment-based question: what is being compared, and what stays the same? If you want a guided path through human physiology, Fermi's AI tutor can work out what you already know and build a plan for the session. For the next chapter in digestion research, read about Ivan Pavlov and digestion.
Tonight, write the 7 August 1825 experiment as a method with an aim, a control and a result, in under eight lines.
