Chemistry Frozen in Time The World Before Black

[00:00:00]In the early 18th century, chemistry was still shackled to frameworks inherited from antiquity. The most dominant was phlogiston theory, the widely accepted belief that combustible materials contained an invisible substance called phlogiston, which was released during burning. German chemist Georg Ernst Stahl had formalized this in the early 1700s, and it held firm across European scientific institutions for decades. It explained combustion, calcination, and respiration in a unified but entirely incorrect way. And because it explained so much, it was extraordinarily resistant to challenge.

[00:00:37]The understanding of heat was no better.

[00:00:40]Most natural philosophers believed heat was a weightless, invisible fluid called caloric, flowing from hot bodies to cold ones. No one had established that different materials absorb heat at different rates, or that heat could be absorbed by matter during a phase change without producing any measurable rise in temperature. These were not just unsolved problems, they were questions nobody had yet framed correctly because the existing model of heat