34 GRAHAM LUSK 



The Beginnings of Calorimetry 



The work of Lavoisier concerning the source of animal heat was in- 

 sufficiently convincing, and so the French Academy^ of Science offered a 

 prize to any one who would produce the best thesis on the subject. The 

 prize was competed for by Despretz and by Dulong. It was awarded in 

 1823 to the former, although in the light of modern knowledge it would 

 seem that the latter had a greater insight into the problem. 



Despretz (1792-1863) gives the following account (1824) : "Xo 

 phenomenon in physiology is more capable of attracting attention than 

 the singular property enjoyed by man and warm-blooded animals of pre- 

 serving an almost constant temperature, although the temperature with 

 which they are surrounded is subject to continual variations. All bodies 

 tend constantly to seek heat equilibrium ; reciprocal exchange tends to 

 establish a uniform temperature between different bodies. 



"Warm-blooded animals, en the contrary, though they are equally 

 exposed to heat loss occasioned by contact, radiation and the evaporation 

 of water, possess within themselves a power to produce heat which main- 

 tains their temperature as a rule at about 39 9 above the melting point 

 of ice." 



The resources of modern science were lacking in the days of Galen, 

 Boerhaave and Haller. The author cites Lavoisier (n) (1780) and criti- 

 cizes Crawford's (1779) very imperfect method. He states that Brodie 

 (1812 Philosophical Transactions) thought the brain produced heatthrough 

 the nerves, citing the heat loss after decapitation. This was denied by Le 

 Gallois, who maintained artificial respiration in a decapitated animal. 



Type of experiment by Despretz: 



Subjects, three guinea-pigs. 



Ventilation, 55 to 60 liters per 2 hours, the air being purified by 



passing through potash. 

 Condition of the environmental air, 6 per cent CO 2 and water 



saturation. 



Experiment 1 : 



CO 2 formed, 2,587 liters. 



O 2 unaccounted (i. e., not in CO 2 ), 0.709 liter. 



The three animals raised the temperature of 23310.5 g. 



water 0.63. 



Animal heat as measured, 100 per cent. 

 Heat due to formation CO 2 69.9 per cent. 

 Heat due to formation water, 19.4 per cent 

 Total heat as calculated, 89.3 per cent. 



