278 Dr. Prout on the Phenomena of Sanguification. [Aprit, 
stances in which the lungs are placed, how oxygen can be passing 
in and vapour passing out through the ‘same membrane at the 
same time. Further we learn, from M. Majendie’s experiments, 
which have been repeated with success by M. Orfila, that phos- 
phorus dissolved in oil, and injected into the jugular vem of a 
dog, is expelled by the mouth and nostrils in the form of copious 
vapours of phosphorous acid,* which could hardly have been 
the case if the phosphorous acid had been formed within the 
vessels ; as in this case, we should have supposed it would have 
remained in solution in the blood, it not being a volatile sub- 
stance. We may, therefore, suppose, that the phosphorus was 
excreted in a state of minute division from the vessels of the 
lungs, and meeting in this state with the oxygen of the atmo- 
sphere, formed the phosphorous acid in question; and if this 
reasoning be admitted with respect to phosphorus, I cannot see 
why it should not be admitted with respect to carbon. 
t has been supposed, as before mentioned, that one use of 
respiration is to convert the chyle into blood, which process is’ 
stated to be effected by the removal of redundant carbon ; and it 
has been maintained in support of this opinion, that more car- 
bonic acid gas is given off when the chyle is supposed to be 
entering the blood. Admitting this use of respiration, the 
manner stated cannot be that in which the change in question is 
effected ; for if it were, animals, after long fasting, and when 
there was no chyle to assimilate, might be supposed to emit 
little or no carbonic acid, and in short to be able to do without 
respiration, which is contrary to observation; besides, many 
animals after eating naturally sleep, in which state itis generally 
acknowledged, that little carbonic acid is given off; but if we 
even admit that more carbonic acid is given off after eating, 
which to a certain extent may be true, this fact may, perhaps, 
be better explamed upon other principles. What then is the 
real nature and use of respiration? Does nothing take place in 
this function but the separation from the blood of a little super- 
fluous carbon? If this were its only use, why are precisely the 
same processes uniformly adopted? Could not this carbon be 
got rid of equally well in various other ways, as, for example, in 
the form of carburetted hydrogen, &c.? Why is oxygen always 
necessary, which apparently never enters the economy, but is 
instantly expelled under the form of carbonic acid? These 
obvious questions have been often asked, and physiologists have 
puzzled their brains to discover a result more adequate to a 
process, so important in the animal economy as respiration ; but 
after all, their labours have not been very successful. Man 
theories have indeed been formed on this subject, and till lately, 
one of them, which supposed animal heat to be the result of the 
respiratory process, was pretty generally admitted; but as the 
* See Experiences pour servir 4 l’Histoire de la Transpiration Pulmonaire: 
Mémoire lu 3 l'Institut. de France, en 1811, p,19,° Also Orfila’s Toxicologie 
Genérale, tom, i. Part If. p, 189. 
