JOSEPH BLACK: BIOGRAPHY, EXPERIMENTS, CONTRIBUTIONS AND DISCOVERIES - BIOGRAPHIES - 2024

Joseph Black (1728-1799) was a Scottish chemist, physicist, teacher, and physician. He carried out his professional work in his native country and is considered one of the most illustrious chemists in the world, as well as one of the founding fathers of modern chemistry.

His meticulous investigative techniques served as an inspiration to others in his day and continue to do so today. His most important contributions focused on the field of thermodynamics, where he established a clear distinction between temperature and heat.

Joseph Black. By Rogers, J

He is also known for his discoveries about magnesia, latent heat, specific heat, and carbon dioxide. He was Professor of Anatomy and Chemistry at the University of Glasgow for 10 years from 1756, and later Professor of Medicine and Chemistry at the University of Edinburgh, where he taught for more than 30 years.

Black lived and worked in the context of the Scottish Enlightenment, a remarkable flowering of intellectual life that occurred in Edinburgh, Glasgow, and Aberdeen during the second half of the 18th century.

He had a very active social life and became an eminent member of the literary and scientific circles of the time. He surrounded himself with famous people such as the philosopher David Hume, the economist Adam Smith, and the geologist James Hutton.

Biography

Early years

Joseph Black was born in 1728 in Bordeaux (France). He was one of the 15 children of John Black, a Scottish-born Ulster wine merchant living in the French city. His mother was Margaret Gordon, born in Aberdeen (Scotland) and who, during his early years, was in charge of Black's education.

Later, at the age of 12, he was sent to the Belfast school to learn Greek and Latin.

University education

In 1746, at the age of 18, he entered the University of Glasgow, where he studied for four years before spending another four at the University of Edinburgh, an institution where he managed to obtain a degree in medicine.

After turning to medicine as a profession, Black came under the tutelage of an innovative chemistry professor, William Cullen. Scottish chemist and doctor Cullen was starting a new chemistry lecture course at the time.

Black became his laboratory assistant before moving to the University of Edinburgh in 1752 to continue his medical studies.

He did not graduate from Glasgow in medicine because he was attracted to the University of Edinburgh, as its faculty enjoyed greater prestige. Before graduating, students had to prepare a thesis.

He was a particularly diligent student and carried out a series of experiments on the chemical properties of an alkali, in particular magnesia alba, now known as magnesium carbonate.

The thesis had to have a medical connection, so Black described the application of this substance to minor digestive disorders. He wrote his work on the treatment of kidney stones with magnesium carbonate. She was awarded the title of medicine in 1754.

Teaching

He was Professor of Anatomy and Chemistry at the University of Glasgow for 10 years starting in 1756, and then Professor of Medicine and Chemistry at the University of Edinburgh from 1766, where he taught and taught for more than 30 years.

In 1766, he decided to follow in the footsteps of William Cullen, his friend and former professor at the University of Glasgow, and moved to Edinburgh as a professor of Medicine and Chemistry.

From that moment, he left research and dedicated himself exclusively to teaching. He managed to increase attendance at his lectures annually for more than thirty years. His talks had a great impact on the dissemination of chemistry.

Black was one of the most popular professors at the University. His chemistry course attracted a large number of students. In addition to introducing cutting-edge topics and meticulously selecting visually appealing experiments, he employed a wide range of successful teaching tools that made chemistry accessible to all of his students.

These students came from all over the UK, the colonies and Europe. Hundreds of them kept their lecture notes and spread their ideas after leaving college.

Last years

Black never married, although it seems that he was popular with the ladies. He was a modest man and an excellent teacher. He had a very active social life and became an eminent member of the literary and scientific circles of the time. He surrounded himself with illustrious figures such as the philosopher David Hume, the economist Adam Smith, and the geologist James Hutton.

On November 17, 1783 he became one of the founders of the Royal Society of Edinburgh. From 1788 to 1790 he was president of the Royal College of Physicians in Edinburgh. In addition, he served on the review committee for the college's editions of the Pharmacopoeia Edinburgensis in 1774, 1783, and 1794.

Black's research and teaching suffered as a result of his poor health. From 1793 his state of health worsened even more and he withdrew little by little from his teaching duties. In 1795, Charles Hope was appointed his curate and in 1797 he gave his last lecture.

Joseph Black died at his home in Edinburgh in 1799 at the age of 71. He is buried in Greyfriars Cemetery, in an area known as the Jail of the Covenanters.

Experiments

Early in his scientific career, Black studied the properties of magnesia alba, a basic magnesium carbonate, which led him to discover what he called "fixed air," now known as carbon dioxide.

This was the first time anyone had shown that air was composed of more than one gas. Also, in 1755 he became the first person to recognize magnesium as an element.

Upon his return to Glasgow in 1756, he met James Watt, who aroused his interest in the properties of objects and substances when heated. His work was the first systematic investigation of what later became known as thermodynamics.

The experiments he undertook led him to discover concepts such as latent heat and specific heat. In addition, they contributed to James Watt's parallel work on the development of the steam engine, and transformed the way heat was measured.

Contributions and discoveries

Analytical balance

Around 1750, while still a student, Black developed the analytical balance based on a slight fulcrum balanced on a wedge-shaped pivot. Each arm carried a pan on which the sample or reference weights were placed.

It far surpassed the precision of any other balance of the time and became an important scientific tool for most chemistry laboratories.

Carbon dioxide

Joseph Black also explored the properties of a gas produced after various reactions. He found that limestone (calcium carbonate) could be heated or treated with acids to produce a gas that he called "fixed air."

After conducting an experiment in which he enclosed a mouse and a lit candle inside a box with CO _{2, he} observed that the fixed air was denser. The mouse died and the candle went out, so he deduced that the air was unbreathable.

Latent heat and specific heat

Black was also interested in the science of heat. In the 18th century there were several contradictory theories about the nature of heat and its relationship to temperature. Black's research not only clarified the difference between temperature and heat, but also resulted in the theory of latent heat.

In 1761 he deduced that the application of heat to ice at its melting point does not cause an increase in temperature, but rather an increase in the amount of water in the mixture.

Likewise, he observed that the application of heat to boiling water does not result in an increase in the temperature of a water / steam mixture, but in a greater amount of steam. From these observations, he concluded that the applied heat had combined with the particles of ice and boiling water to become latent heat.

The theory of latent heat marks the beginning of thermodynamics, which is why it was one of his most important scientific contributions, and on which his scientific reputation is mainly based. He also showed that different substances have different specific heats.

Furthermore, this theory turned out to be very important in the development of the steam engine. The latent heat of water is higher compared to other liquids, which is why it was very useful in James Watt's attempts to improve the efficiency of the steam engine invented by Thomas Newcomen.

Joseph Black and Watt became friends and collaborators after meeting in 1757, while they were both in Glasgow. Black provided significant funding and other support for Watt's early research in the field of steam power.

References

1. Boantza, VD (2016). The enlightenment of joseph black. Annals of Science.
2. Breathnach, CS (2000). Joseph black (1728–1799): An early adept in quantification and interpretation. Journal of Medical Biography
3. Guerlac, H. (1957). Joseph black and fixed air: Part II. Isis.
4. Perrin, CE (1982). A reluctant catalyst: Joseph black and the edinburgh reception of lavoisier's chemistry. Ambix
5. West, JB (2014). Joseph black, carbon dioxide, latent heat, and the beginnings of the discovery of the respiratory gases. American Journal of Physiology-Lung Cellular and Molecular Physiology