1668: Mayow comes close to discovering oxygen

John Mayow (1640-1679)

John Mayow learned by his many experiments that "dark venous blood is changed to bright red by taking up a certain ingredient" in the air, and he referred to this ingredient as "nitro-aerial spirit of air," or "nitro-aerial gas." (11, page 268)(7, page 475)

He also learned that blood exposed to a vacuum gave off bubbles, and he believed this to be "nitro-aerial gas." He was right, and the substance, as later proved, was oxygen. While he did not discover oxygen, he was that close. (7, page 475) (11, page 268)

He was perhaps the first person to actually "grasp the idea that the object of breathing is simply to cause in interchange of gases between the air and the blood, the former giving up its nitro-aerial spirit (oxygen) and taking away vapors engendered by the blood." (11, page 268)

Actually, many experts now believe that Mayow was the first to discover oxygen, although he never received credit because he died at the young age of 35, before his writings were published, and therefore his discoveries were forgotten by history until the 20th century.

However, he did learn that there was indeed a substance in the air, and that it was inhaled by the lungs and "necessary for all forms of life." He did learn that there was indeed a vapor arising from the blood that was exhaled by the lungs. This substance would later be discovered to be carbon dioxide. (7, page 475)

He, therefore, was the first to conclude that respiration was not to cool the blood as previously thought, but for the exchange of gases.  Instead of cooling the lungs, he believed the substance -- this nirto aerial gas -- was absorbed by the blood in the lungs, thus changing its color from dark to bright red.  (7, page 475)

If that wasn't enough, Mayow also discovered that maternal blood supplies an unborn fetus with not just food, but also with "nitro-aerial gas."(11, page 268)(7, page 475)

While he proved that respiration was not to cool the blood, he also proved the blood is not the source of its own heat.  Instead, he proved that heat was produced by the activity of the muscles of the body.  (11, page 268)

Mayow's works were  published in 1668 and 1674, although he died at the early age of 35 before his works were published.  So he was was never recognized until the turn of the 20th century. (7, page 475)

So while he doesn't often get credit by history, Mayow may actually have been the first person to discover oxygen.  Yet, unfortunately, history doesn't give credit for the first to do something, but the first to publish their discovery or invention.  This truth will play out many times in world history.  (7, page 474-5)

References: 

1. Tissier, Paul Louis Alexandre, “Pneumotherapy including aerotherapy and inhalation methods and therapy,” volume x, 1903, Philadelphia, P. Blakiston’s Sons & Co., page 19
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7. Hill, Leonard, Benjamin Moore, Arthur Phillip Beddard, John James Rickard, etc., editors, "Recent Advances in Physiology and bio-chemistry," 1908, London, Edward Arnold
8. Hamilton, William, "A History of Medicine, Surgery and Anatomy," 1831, Vol. I, London, New Burlington
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10. Osler, ibid, pages 170, reference referring to William Harvey: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, Francofurti, 1628, G. Moreton's facsimile reprint and translation, Canterbury, 1894, p. 48. 20 Ibid., p. 49.
11. Garrison, Fielding Hudson, "Introduction to the history of medicine," 1921, London, 
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13. Garrison, op cit, 266; (Samuel) Pepy's Diary, Mynors Bright's ed., London, 1900, v, 191
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