208* 



1.0300 ; and that of venal blood 0.8928. Among 

 elastic fluids, the specific heat of oxygen gas, com- 

 pared with that of water, is as 4.749O to 1 .OOOO : of 

 nitrogen, the specific heat is 0.7936 : of atmospheric 

 air, 1.7900: and of carbonic acid gas, 1.6454*. 

 This high specific heat of oxygen gas, is productive 

 of very important effects in the operations both of 

 nature and art. The power of this gas to supply 

 heat, says M. Berthollet, is well known, and there 

 is no substance which suffers so much of it to escape 

 by the changes of its constitution. In the forma- 

 tion of water by the combustion of oxygen and hy- 

 drogen gases, the greater part of the heat might at 

 first be supposed to proceed from the condensation 

 of the latter ; but solid bodies, as phosphorus, occa- 

 sion the greatest emission of heat by combining with 

 a given quantity of oxygen ; and when water is de- 

 composed by sulphuric acid and iron, much heat is 

 given out, and nevertheless all the hydrogen of the 

 water resumes its elastic form. This heat therefore 

 must, he adds, have proceeded from a change in the 

 state of the oxygen of the water, which gives only a 

 small part of that which it yields, by combining with 

 the iron, to enable the hydrogen to assume the gase- 

 ous form t- We now proceed to apply these facts 

 to the illustration of our present subject. 



1 66. Through the whole of our inquiry it has ap- 

 peared, that the oxygen gas of the air is converted 

 into carbonic acid by the living processes which have 



* Crawford on Animal Heat, 

 f Chemical Statics, vol. ii. p. 15. 



