  Spain was a scientifically backward country in the early 19th-century. The
causes were various political events, the War of Independence, and the reign of
Fernando VII. The introduction of contemporary physics into textbooks was
therefore a slow process. An analysis of the contents of 19th-century Spanish
textbooks is here presented, centred on imponderable fluids, the concept of
energy, the mechanical theory of heat, and the kinetic theory of gases.
