358 
experiment was repeated, and with nearly the same 
results ; but as the temperature of the room and of 
the body were lower than in the former experiment,, 
the effects were not so distinct. 
668. The foregoing experiments seem clearly to 
establish the existence ol carbonic acid in air that 
has been kept in contact with the skin ; and this acid 
gas must have been either formed by the action of 
the skin upon the surrounding air, or emitted ready 
formed JDy that organ ; for no trace of carbonic acid 
could be discovered in the air before it was submit- 
ted to experiment. Now the experiments of Dr 
Klapp (663.) seem decisive against the supposition 
that gaseous fluids emanate from the skin ; so that 
we are compelled to consider this acid gas as formed 
by the union of the oxygen of the air with the ani- 
mal carbon, precisely in the same manner as it is 
formed by the skins of the lower animals (662.), 
and also by the respiratory organs of man himself. 
Dr Mackenzie ascertained, that, in these experiments, 
the carbon did not proceed from the oiled silk ; for 
when the same silk was kept for 48 hours in contact 
with air, it produced in it no trace of carbonic acid. 
669. The effects produced in the air by animal 
solids and fluids, after their removal from the living 
body, confirm, in all respects, the belief that they 
contain carbon in a state fitted to combine with oxy- 
gery^as. We have seen that both the serum of the 
blood (97.) and the entire mass of that fluid, convert 
the oxygen gas of the air into carbonic acid ; and si- 
milar effects are produced by the other animal fluids. 
So, likewise, moistened bladders (587.) act equally 
