1.1 Definition and History

What do bread and chocolate, hair and finger-nail clippings, coal and rubber, ointments and suppositories, explosives, kidney stones and ancient Egyptian papyri have in common? Many interesting answers could probably be suggested, but the connection wanted in this context is that they all undergo interesting and practically important changes on heating.

The study of the effect of heat on materials obviously has a long history, from man's earliest attempts at producing pottery, extracting metals (about 8000 BC) and making glass (about 3400 BC) through the philosophical discussions of the alchemists on the elements of fire, air, earth and water, to early work on the assaying of minerals (about 1500 AD), followed by the development of thermometry and calorimetry ^[1], ^[2]. Only in the late 19th century did experiments on the effect of heat on materials become more controlled and more quantitative. Much of this work depended upon the development of the analytical balance which has its own interesting history ^[3], ^[4]. Some milestones in the development of thermal measurements are given in Table 1.1.