Adair Crawford

In existographies, Adair Crawford (1748-1795) (CR:2) was an English chemist, physician, and surgeon, noted for []

In 1776, Crawford travelled to Scotland where he attended, as has been conjectured (Cardwell, 1971), the chemistry lectures of William Irvine, having an interest in solving the problem of the nature of animal heat via comparing the specific heats of inhaled air (oxygen and nitrogen) vs exhaled air or "fixed air" (carbon dioxide) as it was then called. [1]

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The following are quotes on Crawford:

“About the year 1780, it was distinctly proved that the same weights of different bodies require unequal quantities of heat to raise them through the same temperature, or give out unequal quantities of heat on cooling through the same number of thermometric degrees. It was recognized that for different bodies the unequal quantities of heat, by which the same weights of different bodies are heated through the same range, must be determined as special constants, and considered as characteristic of the individual bodies. This newly discovered property of bodies, Wilcke designated as their ‘specific heat, while Crawford described it as the ‘comparative heat’, or as the capacity of bodies for heat.
— Hermann Kopp (1865), “Investigations of the Specific Heat of Solid Bodies” [2]

“In 1779, Crawford published an account of his experiments and observations in the form of a book on animal heat. Crawford measured the specific heats of a large number of inorganic and organic substances and, something quite new, the specific heats of common air and ‘fixed air’ (carbon dioxide). This he did by filling a bladder with the two airs and comparing the heating and cooling effects they had on a given amount of water at a known temperature. He concluded that the ‘specific heat’ of fixed air was much smaller than that of ordinary air, only 1/67 in fact. Hence, as in respiration one breaths in ordinary air an exhales fixed air with a much reduced heat capacity there must, on Irving’s principles, be a substantial emission of heat as a result of the change. Perhaps this was the real cause of animal heat? In his second and much expanded edition of the work (1788) Crawford described experiments using brass containers in place of bladders for the measurement of the specific heat of gases. The results, of course, could had have been accurate, and he had no appreciation of the fact that in the first experiments, in principle at any rate, he had been measuring the specific heats of gases at constant pressure (Cp) and in the second at constant volume (Cv).”
Donald Cardwell (1971), From Watt to Clausius (pg. 57)

1. Cardwell, Donald S.L. (1971). From Watt to Clausius: the Rise of Thermodynamics in the Early Industrial Age (pgs. 56-57). Cornell University Press.
2. Kopp, Hermann. (1865). “Investigations of the Specific Heat of Solid Bodies”, Journal of the Chemical Society, 4(19): 154-234.

Further reading
● Crawford, Adair. (1779). Experiments and Observations on Animal Heat. London.
● Crawford, Adair. (1788). Experiments and Observations on Animal Heat. London.

External links
Adair Crawford – Wikipedia.

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