Drudgery. That’s how I envisioned the research effort needed to support my book writing. Perhaps it was the painful flash backs associated with working with microfilm that triggered this. Regardless, I wasn’t looking forward to it.

Given this, I was pleasantly surprised to discover how enjoyable the research was, especially after finding numerous insightful publications by science historians on the evolution of thermodynamics. One such publication, Historic Researches. Chapters in the History of Physical and Chemical Discovery by Thomas Wightman Chalmers (here) told me the history behind the science of calorimetry and the doctrines of sensible and latent heats. Here’s a relevant excerpt from my book (p. 204) on this topic.

The heat capacity experiments of Joseph Black

“In a set of rather clever experiments that arguably founded the science of calorimetry, Joseph Black (1728-1799), British chemist and physicist, famed for his development of calorimetry, which contributed greatly to the subsequent development of thermodynamics, quantified the heat associated with melting ice and evaporating water. In a large room maintained at constant temperature (47^oF), he hung two glass globes, one containing ice (32^oF) and the other water (33^oF), and then measured the temperature in each over time. He found that the water heated to 40^oF in about 30 minutes and that the ice melted and then also rose to 40^oF in about 10 ½ hours. Assuming an equal rate of heat flow from the room to the globes, he concluded that the heat absorbed by the ice was 21 times the heat absorbed by the water to get to the same 40^oF final temperature. Using this same general method but naturally with a source of heat at higher temperature, Black and his assistant, James Watt—yes, he of the steam engine—were also able to quantify the relative heat absorbed by heating and boiling water. Applying simple math to these results and using modern terminology, Black measured a latent heat of melting of ice of 139 Btu/lb and a latent heat of vaporization of water of 850 Btu/lb, each reasonably close to their currently known values of 144 Btu/lb and 970 Btu/lb.”

I loved Black’s simple, intelligent approach to these critical experiments and equally loved how Chalmers captured them. Both jobs well done.

Learn more about heat capacity

The study of heat capacity became an area of intense focus in thermodynamics as it provided the means to connect macroscopic properties with microscopic behavior, especially for gases. Explore more on this topic in my book, Block by Block – The Historical and Theoretical Foundations of Thermodynamics.

[1] Chalmers, Thomas Wightman. 1952. Historic Researches. Chapters in the History of Physical and Chemical Discovery. Charles Scribner’s Sons. pp. 89-93.