181 



purity with that of the atmosphere * ; so that when 

 living action had ceased in these animals, no change 

 was produced on the air in contact with them. 



143. Nor are these effects peculiar to those ani- 

 mals which change the air by the mediation of their 

 skin : they are common also to those which breathe 

 by lungs. A marmot that was cold to the touch, 

 and so closely rolled up as to be tossed about and 

 irritated in every shape without exhibiting the slight- 

 est indication of life, was exposed in a recipient of 

 atmospheric air, inverted over mercury, to a tempe- 

 rature -12 Reaumur. He continued motionless 

 three hours and a half, during which time the mer- 

 cury in the jar remained stationary : and the air, on 

 being analysed, was found in every respect similar 

 to that of the room in which the experiment was 

 made f- The same animal was then transferred in- 

 to ajar of carbonic acid at temperature 12.5 Reau- 

 mur, where he remained four hours without shewing 

 the least sign of motion, or suffering the smallest in- 

 jury ; but a rat, put at the same time into the jar, 

 died almost instantly ; and when, in a second expe- 

 riment, the temperature was raised to zero, the mar- 

 mot also began to breathe, and then speedily died in 

 a jar of this gas. These facts prove, not only that the 

 carbon, which decomposes the air, is in every case fur- 

 nished by the animal, but that its emission depends 

 wholly on the state of the circulating fluids ; for, as 

 the circulation increased, declined, or ceased, so like- 

 wise did the emission of carbon, and consequent pro- 



* Memoirs, p. 197. 203. f Ibid. p. 333. et seq. 



M3 



