Dr. Bdl on Animal Heat. 77 



a room the air of which was heated to a degree far above 

 that of the human blood ; although they remained there 

 sometimes for the space of half an hour, yet the heat of 

 their bodies was not increased by more than three or four 

 degrees. 



It is interesting to find that Dr. Bell, in criticising this 

 paper, struck a right key, and gave a good tone to the young 

 society. He says, ' We are compelled to refuse credit to the 

 assertion even of Dr. Fordyce, that there was no evaporation. 

 The evaporation must have been great, and would diminish 

 the effect of the external heat by surrounding the surface 

 with a cool atmosphere.' It is true that Dr. Bell says that 

 ' the cause of animal heat remains unknown/ and he is not 

 fully aware of the great amount of heat carried off by the 

 evaporating water, still his mode of reasoning is sound. 



We see that, unable as he confesses himself to solve the 

 whole problem, he succeeds in guiding out of the way of 

 error, and as we may say, criticising with some vigour a 

 publication sanctioned by the Royal Society. 



The action of oxygen was only beginning to be under- 

 stood, and its name was not familiar to chemists ; heat was 

 still a substance however subtle and strange, and phlogiston 

 was a component part of metals, for some years after this, 

 even to the mind of Cavendish. Notwithstanding this belief 

 Priestley and Lavoisier were Honorary Members of the 

 Society, and the former had in 1775 discovered oxygen, 

 calling it pure or dephlogisticated air. 



Such a subject as heat was a fine key-note for the 

 Society. The tune that followed has been played well, and 

 the mechanical theory of heat has been developed by one 

 of our still living members, and begun to change the face of 

 the world by penetrating into most of its science and into 



