The Science of Heat at the Beginning of the 19th Century

  So far our understanding of heat hasn't advanced much beyond what was known in the 1st decade of the 19th Century. Dalton in 1801 was the first to note that the relative expansion of gases with temperature was approximately the same for all gases. A year later Gay-Lussac published experimental results for the expansion of air, hydrogen, oxygen and nitrogen. In 1807 Young published a lecture on heat which touched on the measurement of the expansion of solids with changes in temperature and noted that the mercury thermometer may be off by 2 or 3 degrees Fehrenheit mid scale. Since heat was produced by friction he concluded that it was not a substance but instead a quality being associated with both the motion of the constituent particles of a body and the motion of a medium in the case of radiation. At the end of the same year the scientific community got a preliminary look at Fourier's Theory of Heat.

To improve one's understanding of heat one needs to take a closer look at cooling and heating and the mechanisms of the conduction and radiation processes. The study of heat was focused on this during much of the remainder of the 19th Century.

Bibliography

Dalton - On the Expansion of Elastic Fluids by Heat (1801)

Gay-Lussac - Recherches sur la dilatation des gaz et des vapeurs (1802)

  Art. IV. Expériences et résultats.

Gay-Lussac - Researches upon the Rate of Expansion of Gases and Vapors

  Part IV. Experiments and Results

Young - On the measures and the nature of heat (1807)

Fourier - Mémoire sur la Propagation de la Chaleur dans les Corps Solides (1807)