f 250 J 
LI. New Outlines af Chemical Philosophy. By Ez. WatkzR, 
Esq. of Lynn, Norfolk. 
[Continued from p. 105.] 
On Respiration. 
Lynn, March 28, 1814. 
Sins, —Lr has been ascertained by philosophers who have writ- 
ten on the respiration of animals, that no air passes through the 
membrane of the lungs into the blood, for the same quantity of 
air that enters the lungs is returned again into the atmosphere, 
but its properties are changed. Messrs. Allen and Pepys have 
proved by a series of experiments, that ‘when atmospheric air 
alone is respired, no other change takes place in it, than the sub- 
stitution of a certain portion of carbonic acid gas for an equal 
volume of oxygen *.” 
And Mr. Ellis observes, that “ in man, as well as in the lower 
animals, the conversion of oxygen gas into carbonic acid con- 
stitutes the only essential change which the air of our atmo- 
sphere experiences in the lungs during its respiration}.” 
The modes in which the atmosphere is depraved by the living 
functions of animals, is a chemical process which has never been 
clearly explained. But from the preceding theory of combus- 
tion ft, the changes induced on the air, and on the temperature 
of the blood, in respiration, will admit of an explanation which 
may not be deemed unsatisfactory. 
Part of the thermogen which is contained in the air, taken 
into the lungs, passes through their thin membrane into the 
blood, in the same manner as the electric fluid passes through 
this or any other animal matter, and, meeting with photogen, 
generates animal heat, in a manner which will be more fully ex- 
plained hereafter. 
But the generation of carbonic acid gas in the lungs may be 
explained thus : 
Let Q represent a quantity of oxygen gas contained in the 
lungs, and let it be divided into two parts, a = the greater part, 
and ) = the less: then a+b=Q. 
Let the thermogen in LJ be attracted into the blood by the 
photogen which it contains, and @ will represent the oxygen 
gas remaining. Suppose a attract a quantity of carbon from the 
exhalant vessels of the lungs =c=/; then the whole quantity 
Q will become carbonic acid gas, when Q is divided according 
to the proportion of oxygen and carbon which a given quantity 
of that gas contains. 
* Phil. Trans. 1809, p. 427. + D. Ellis on Atmospheric Air. 
+ Phil. Mag. vol. xlu. p. $67; and vol. xlii. p. 22. 
According 
