1757: Joseph Black discovers carbon dioxide

Joseph Black (1728-1799)

In 1668 John Mayow came very close to discovering oxygen and carbon dioxide. Perhaps the only thing stopping him from these discoveries was an early death. This left the door open for other investigators, such as Joseph Black.

In the 13th century, and again in the 17th century, Roger Bacon and Jean van Helmont described a substance they referred to as gas sylvestre.

In 1668, John Mayow noted his belief that there was a vapor arising from the blood that was exhaled during the act of respiration. Yet he passed away before he was able to make anything further of this discovery.

Other investigators performed experiments with this substance throughout the 18th century, and by the 1750s, by the time Joseph Black began his experiments with the gas, it was generally referred to as "fixed air."

So, while performing his own experiments in 1757,  Black essentially proved proved Bacon, van Helmont and Mayow correct, that a substance, be it called "gas sylvestre" or "fixed air" does exist.

By his experiments, he proved that by heating limestone the substance was released into the atmosphere.  He also proved that this substance was exhaled during the process of respiration.

Also of significance is that Black discovered that this compound was formed animals and exhaled by the lungs, thus proving Mayow correct. A picture was now forming that the purpose of the lungs was not to cool the body, but to inhale a substance vital to life, and exhale a waste product (carbon dioxide).  This wisdom would be expounded upon by great minds of the next century.

So, beginning in the 13th century, various men of genius began to question the ideas of the ancients, those that were held by the Church.  Many of them risked everything to perform, and later to announce, their discoveries to the world.  Such bravery allowed for science to slowly replace mythology in medicine.

References:

1. Tissier
2. Lagerkvist, Ulf, "The Enigma of Ferment," 2005, Singapore, World Scientific Publishing
3. Potter, Elizabeth, "Gender and Boyle's Law of Gases," 2001, Indiana University Press
4. Newman, William R, et al, "Alchemy Tried in the Fire," 2002, University of Chicago
5. Lehrs, Ernst, "Man or Matter," 1958, Great Britain, Whistable Litho Ltd.
6. Jindel, S.K., "Oxygen Therapy," 2008, pages 5-8
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
9. Osler, William Henry, "The evolution of Modern Medicine: A series of lectures delivered at Yale University on the Sillman Foundation in April, 1913," 1921, New Haven, Yale University Press
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, 
12. Baker, Christopher, editor, "The Great Cultural Eras of the Western World: Absolutism and the Scientific Revolution 1600-1720: A biographical dictionary," 2002, CT, Greenwood Publishing; Herman Boerhavve published Biblia Naturae (Bible of Nature) in 1737, which was a two volume compilation of the works of Jan Swammerdam. Can you read Latin?
13. Garrison, op cit, 266; (Samuel) Pepy's Diary, Mynors Bright's ed., London, 1900, v, 191
14. Bradford, Thomas Lindsley, writer, Robert Ray Roth, editor, “Quiz questions on the history of medicine from the lectures of Thomas Lindley Bradford M.D.,” 1898, Philadelphia, Hohn Joseph McVey
15. Brock, Arthur John, "Galen on the natural faculties," 1916, London, New York, William Heinemann, G.P. Putnam's Sons
16. "History of Chemistry," historyworld.net, http://www.historyworld.net/wrldhis/PlainTextHistories.asp?ParagraphID=kpt, accessed 7/6/14
17. Affray, Charles, Denis Noble, "Origins of Systems Biology in William Harvey's masterpiece on the Movement of the Heart and the Blood in Animals," April 17, 2009, International Journal of Molecular Sciences, 10(2), pages 1658-1669, found online at ncbi.nlm.hih.gov, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680639/, accessed 7/8/14

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1750: Purpose of air, breathing is learned

Stephen Hales (1677-1761) 

So we are now in the year 1750 sitting among a group of fellow students at the University of Glasgow. The topic for today, says our instructor in his usual monotone manor, is the purpose of air.

He reminds us that in 1553, Michael Servetus was the first to speculate that it was the lungs that caused dark blood to become bright red, and not the heart.

In 1640, he says, William Harvey was the first to describe the systemic circulation of the blood through the vessels of the body.

In 1667, Joachim Becher published a book, "Physical Education," in which he said the four classic elements of fire, earth, air and water were no longer relevant, and replaced them with three earth forms: terra lapidea, terra fluida, and terra pinguis.  He believed terra pinguis was responsible for combustion and rusting.

Joseph Black (1728-1799)

In 1697 George Ernst Stahl changed this theory slightly and used the term phligoston (Greek term for burning up) to describe a material or principle of fire (not the fire itself) that was released into the air during combustion.  When a substance was burned, the combustible components of the burned material were released into the air, thus causing it to become impure.

This theory, says our instructor, is the generally accepted theory of today. However, it must be known that another theory, that substances are formed from atoms, that is beginning to be more generally accepted in our time.  However, before we get to that discussion let's continue our history.

In 1668, John Mayow was the first to speculate that the purpose of the lungs was not to cool the heart, but for the exchange of gases.  He believed a substance in the air -- nitro-aerial gas -- was inhaled into the lungs, and when it entered the blood stream the blood turned from a dark color to a bright red.  This, he speculated, was why venous blood was dark and arterial blood red.

He also speculated that a vapor produced by the blood was exhaled by the lungs. He did not know that nitro-aerial gas was oxygen, and he did not know that the substance produced by the blood and exhaled by the lungs was carbon dioxide. He may have made these discoveries had he not died at the young age of 35, before any of his works were published.

In 1727 and 1733 Stephen Hales published the results of experiments on air and respiration where he proved that there is no circulatory system in trees like there is in humans and animals.  (2, page 193)

So, by 1750, our present year, investigators had determined that one of these gases was fixed air that was exhaled by the lungs, and the other was a vapor that was inhaled by the lungs.

One of the students in our class is Joesph Black.  He would go on to become the first to recognize that this gas was burned off during the exhalation phase of respiration.   He discovered it "was deadly to animals, and could distinguish a flame." (1) (2, page 193-194)

References:

1. "Carbon Dioxide,"  Scienceclariied.com, http://www.scienceclarified.com/Ca-Ch/Carbon-Dioxide.html#b, observed the site on May 4, 2012 (this information is available at a variety of sources, although I chose to give sciencedaily.com credit)
2. Magner, Lois N., "History of Life Sciences," 2002, 3rd edition, New York, Marcel Dekker

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