68 FKAGMENTS OF SCIENCE. 



Percentage of Carbonic Acid in the Human Breath. 



Chemical analysis Physical analysis 



4-66 4-56 



5-33 5-22 



It is thus proved that in the quantity of ethereal 

 motion which it is competent to take up, we have a prac- 

 tical measure of the carbonic acid of the breath, and 

 hence of the combustion going on in the human lungs. 



Still this question of period, though of the utmost 

 importance, is not competent to account for the whole 

 of the observed facts. The ether, as far as we know, 

 accepts vibrations of all periods with the same readiness. 

 To it the oscillations of an atom of free oxygen are just 

 as acceptable as those of the atoms in a molecule of 

 olefiant gas; that the vibrating oxygen then stands so 

 far below the olefiant gas in radiant power must be re- 

 ferred not to period, but to some other peculiarity. The 

 atomic group which constitutes the molecule of olefiant 

 gas, produces many thousand times the disturbance 

 caused by the oxygen, it may be because the group is 

 able to lay a vastly more powerful hold upon the ether 

 than the single atome can. Another, and probably 

 very potent cause of the difference may be, that the 

 vibrations, being those of the constituent atoms of the 

 molecule,* are generated in highly condensed ether, 

 which acts like condensed air upon sound. But what- 

 ever may be the fate of these attempts to visualise the 

 physics of the process, it will still remain true, that to 

 account for the phenomena of radiation and absorption 

 we must take into consideration the shape, size, and con- 

 dition of the ether within the molecules, by which the 

 external ether is disturbed. 



* See ' Physical Considerations,' Art. iv. p. 102. 



