PeterDisAbelard. said...
The way the caloric content of foods was determined is with a device called a Bomb Calorimeter which is a small, strong metal container suspended in a container of water. Inside the container is a small amount of the dried food and enough oxygen to ensure that it burns completely. They use a spark to light the food on fire and determine how much heat is produced by measuring how much the temperature of the water rises.
But, PDA, did you know that the very
first calorimeter was an "ice calorimeter," a la
CAdogsRus's suggestion, to measure caloric content. The method relied on the heat required to melt ice to measure the heat evolved from chemical reactions—they measured how much water accumulated after melting—long before the controlled burns of the "bomb calorimeter" were feasible.
Scholars Lavoisier and Laplace—yes,
that Lavoisier and
that Laplace—are typically associated with the first use of the ice calorimeter. Sadly, the two brilliant scientists met far different fates: Lavoisier was guillotined as part of the craziness of the French Revolution for having complained that "the state of public affairs in France...has temporarily retarded the progress of science and distracted scientists from the work that is most precious to them." French mathematician Joseph-Louis Lagrange remarked that "it took them only an instant to cut off that head, and a hundred years may not produce another like it." Eighteen months after his Reign of Terror murder, he was exonerated by the government, and his belongings were returned to his widow along with a note which read: "To the widow of Lavoisier, who was falsely convicted". I've seen a re-creation of his lab at Musée des Arts et Métiers in Paris.
Laplace (known as the French Newton) prudently left Paris during the worst parts of the Revolution, but returned to be graced with several titles by his former student Napoleon Bonaparte who seized control as the country struggled to recover from the Revolution's ravages under the unpopular Directory. Having lived so much longer than Lavoisier (his life was >50% longer), his amazing list of scientific accomplishments is more substantial; including his fundamental contributions to the least squares & central limit theorem, the dynamic theory of tides (building on Newton and Bernoulli's work), his (the first) theories on black holes & gravitational collapse, and finally the mathematical transformation which many of us know him by which bears his name. Laplace eventually achieved the esteemed rank of marquis following the Bourbon Restoration.
Anyhow, they used ice because the phase change/heat capacity was understood then, and it became the standard from which all other materials are gauged (the specific heat of water would be defined as 1 cal/(K⋅g)). Ice cream is a blend in which the heat content would vary flavor-to-flavor. Ben & Jerry's Coffee Coffee Buzz Buzz has the most energy...!
Post Edited (NKinney) : 6/5/2018 2:16:32 PM (GMT-6)