363 
674. But whether the carbon, furnished by ani- 
mal bodies, escape by virtue of a living action, or 
whether it be afforded under those spontaneous 
.changes which all organised bodies experience, the 
actual combination of this substance v/ith oxygen gas 
is purely chemical, and to this combination, effects, ap- 
parently similar, seem to succeed. Thus, by expo- 
sure to oxygen gas, black blood is rendered red, as 
well after its removal from the body, as during its 
transmission through the lungs ; and so, likewise, 
recently cut flesh often appears nearly black, but, 
by exposure to the air, it assumes a florid hue. What- 
ever, therefore, be the mode in which the carbon is 
supplied to act on the air, the sensible effect produ- 
ced in the animal fluids, both during life and after 
death, is precisely the same, and must, therefore, be 
equally referred to the operation of a chemical ac- 
tion. 
675. But although the union between oxygen gas 
and carbon be, in all cases, purely chemical, and the 
immediate effects to which it gives rise, both during 
the continuance of living action and under spontane- 
ous decomposition, be precisely the same ; yet the 
facts, which have now been detailed, sufficiently es- 
tablish a difference in the mode in which this carbon 
is supplied. For in the living body, the emission of 
sun, the action was immediately accomplished. It may be pro- 
per to add, that when, in these experiments, the tubes have been 
closely stopped, the carbonic acid is not detected, till after the 
gas has been repeatedly transmitted through lime water, its 
appearance at first being prevented by the presence of muriatic 
acid gas. 
