We owe the invention of calorimetry to him: Who is Joseph Black?

(1728-1799) Scottish physician, chemist, and physicist. As a result of his studies on carbonate compounds, he defined carbon dioxide gas, developed the concepts of latent and specific heat, and laid the foundation of calorimetry. He was born on April 16, 1728, in Bordeaux, France. One of the twelve children of a Scottish merchant who settled in this country, Joseph Black was sent to Scotland in 1740 for his education. After learning Latin and Greek at a private school, he began his medical studies at Glasgow University. Here he followed the lectures of William Cullen, one of the well-known chemists of his time, and worked as a laboratory assistant for three years. He continued his education at Edinburgh University in 1751. His doctoral thesis, "De Humore acido a cibis orto et magnesia alba", which he submitted in Latin in 1754, is considered one of the classics of chemistry. Joseph Black, who added his studies on alkalis to his thesis, which includes various reactions of magnesium carbonate, was published in English in 1756 as Experiments Upon Magnesia Alba, Quicklime, and Some Alkaline Substances.

Joseph Black (16 April 1728 – 6 December 1799) was a Scottish physicist and chemist, known for his discoveries of magnesium, 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 then Professor of Medicine and Chemistry at the University of Edinburgh from 1766, teaching and lecturing there for more than 30 years.

After Cullen's appointment as professor of chemistry at Edinburgh University, he was appointed to Glasgow University in 1756, the place vacated by Cullen. His first studies here were in the fields of latent and specific heat concepts. In these works, for the first time, the difference between the concepts of heat and temperature began to become clear. Ten years later, he was appointed to the position vacated by Cullen, this time at Edinburgh University. Joseph Black had a widespread reputation not only as a good physician and chemist but also as a teacher. Famous chemists of the period followed his lectures as well as students from various countries. Joseph Black, who did not teach after 1796 due to his deteriorating health, died in Edinburgh on 10 November 1799.

Black's work in chemistry is of medical origin. He chose this topic as his doctoral thesis after two professors at Edinburgh University made statements about the dissolution of bladder and kidney stones by alkaline substances. Joseph Black began his studies by studying Magnesia alba, which is used as a mild laxative. When he evaluated the results of his experiments, he observed that the reactions of magnesium carbonate were similar to the reactions of limestone (calcium carbonate). When both substances were heated, a certain percentage of their weight was lost. In addition, the foaming observed in the reaction of white magnesia with acids was not observed in such reactions of caustic alkalis. Joseph Black then concluded that there is a difference in the ratio of a "constant gas" between alkaline carbonates (soft alkalis) and caustic alkalis. It was understood in a short time that this gas, which is obtained by heating alkali carbonates, has different properties from air. Joseph Black named this different gas, which was first described as a separate gas in the early 17th century by van Helmont, and later called "carbon dioxide", as "fixed air" because it always causes a constant weight loss in the reactions; studied its physical and chemical properties. He discovered that this gas was also produced by fermentation and combustion of charcoal, as well as in the atmosphere and breath. He proved the impossibility of combustion in this gas, and that after the candle burns in a closed glass container, it goes out in the air that turns into carbon dioxide. Later, Black's student Rutherford (1749-1819) continued his work on this subject.

In another important work, Black showed that temperature and heat are different concepts. The temperature has been measured with a thermometer since Galileo. In thermometers, the grading is done by taking the points where the water turns into ice and evaporates as constant and dividing the difference into certain slices.

When Black observed the melting process of ice, he noticed that the temperature did not change during the melting period. In that case, the melting event could not be defined with the concept of temperature. Revealing that the same situation is in question in evaporation, Black developed the latent heat theory regarding state changes. Here he showed the existence of heat energy other than that which causes the temperature rise and that this energy is different for melting and evaporation. In addition, according to the principle of conservation of energy, this latent heat would also be converted into energy as the steam turns into water. This phenomenon was used by James Watt in the development of the steam engine.

Another discovery of Black is specific heat. After the concept of heat energy emerged, Black, who examined the states of different substances against this energy, revealed that two same substances that received the same amount of heat came to different temperatures. Specific heat is the heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius. The importance of Black's observational discoveries regarding the concepts of latent and specific heat is better understood by Maxwell's theory of kinetic heat.

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Black’s balance

https://www.chemistryworld.com/opinion/blacks-balance/4013872.article